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  • Articles  (183)
  • Biochemistry  (134)
  • Binding Sites  (49)
  • 1995-1999
  • 1990-1994  (183)
  • 1915-1919
  • 1990  (183)
  • 1917
  • Computer Science  (183)
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  • Articles  (183)
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  • 1995-1999
  • 1990-1994  (183)
  • 1915-1919
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  • 1
    Publication Date: 1990-08-17
    Description: The transcription factor C/EBP uses a bipartite structural motif to bind DNA. Two protein chains dimerize through a set of amphipathic alpha helices termed the leucine zipper. Highly basic polypeptide regions emerge from the zipper to form a linked set of DNA contact surfaces. In the recently proposed a "scissors grip" model, the paired set of basic regions begin DNA contact at a central point and track in opposite directions along the major groove, forming a molecular clamp around DNA. This model predicts that C/EBP must undertake significant changes in protein conformation as it binds and releases DNA. The basic region of ligand-free C/EBP is highly sensitive to protease digestion. Pronounced resistance to proteolysis occurred when C/EBP associated with its specific DNA substrate. Sequencing of discrete proteolytic fragments showed that prominent sites for proteolysis occur at two junction points predicted by the "scissors grip" model. One junction corresponds to the cleft where the basic regions emerge from the leucine zipper. The other corresponds to a localized nonhelical segment that has been hypothesized to contain an N-cap and facilitate the sharp angulation necessary for the basic region to track continuously in the major groove of DNA.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shuman, J D -- Vinson, C R -- McKnight, S L -- New York, N.Y. -- Science. 1990 Aug 17;249(4970):771-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Research Laboratories, Department of Embryology, Baltimore, MD 21210.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2202050" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; CCAAT-Enhancer-Binding Proteins ; Chromatography, High Pressure Liquid ; DNA/*metabolism ; DNA-Binding Proteins/metabolism ; Kinetics ; Leucine ; Macromolecular Substances ; Models, Molecular ; Molecular Sequence Data ; Nuclear Proteins/*metabolism ; Peptide Fragments/metabolism ; Peptide Hydrolases/*metabolism ; Protein Conformation ; Transcription Factors/*metabolism ; Trypsin/metabolism
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  • 2
    Publication Date: 1990-07-06
    Description: Oligonucleotides equipped with EDTA-Fe can bind specifically to duplex DNA by triple-helix formation and produce double-strand cleavage at binding sites greater than 12 base pairs in size. To demonstrate that oligonucleotide-directed triple-helix formation is a viable chemical approach for the site-specific cleavage of large genomic DNA, an oligonucleotide with EDTA-Fe at the 5' and 3' ends was targeted to a 20-base pair sequence in the 340-kilobase pair chromosome III of Saccharomyces cerevisiae. Double-strand cleavage products of the correct size and location were observed, indicating that the oligonucleotide bound and cleaved the target site among almost 14 megabase pairs of DNA. Because oligonucleotide-directed triple-helix formation has the potential to be a general solution for DNA recognition, this result has implications for physical mapping of chromosomes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Strobel, S A -- Dervan, P B -- GM 42966/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Jul 6;249(4964):73-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Arnold and Mabel Beckman Laboratories of Chemical Synthesis, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena 91125.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2195655" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Binding Sites ; Chromosomes, Fungal/*metabolism ; DNA, Fungal/*genetics/metabolism ; Densitometry ; Hydrogen-Ion Concentration ; Molecular Sequence Data ; Nucleic Acid Conformation ; Nucleic Acid Hybridization ; Oligonucleotides/*genetics/metabolism ; Saccharomyces cerevisiae/*genetics
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  • 3
    Publication Date: 1990-05-18
    Description: Most proteins destined for export from Escherichia coli are made as precursors containing amino-terminal leader sequences that are essential for export and that are removed during the process. The initial step in export of a subset of proteins, which includes maltose-binding protein, is binding of the precursor by the molecular chaperone SecB. This work shows directly that SecB binds with high affinity to unfolded maltose-binding protein but does not specifically recognize and bind the leader. Rather, the leader modulates folding to expose elements in the remainder of the polypeptide that are recognized by SecB.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Randall, L L -- Topping, T B -- Hardy, S J -- GM 29798/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 May 18;248(4957):860-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Biochemistry/Biophysics Program, Washington State University, Pullman 99164-4660.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2188362" target="_blank"〉PubMed〈/a〉
    Keywords: *ATP-Binding Cassette Transporters ; Bacterial Proteins/*metabolism ; Binding Sites ; Biological Transport ; Carrier Proteins/*metabolism ; Cytosol/metabolism ; Escherichia coli/*metabolism ; *Escherichia coli Proteins ; Maltose-Binding Proteins ; Molecular Weight ; *Monosaccharide Transport Proteins ; Protein Conformation ; Protein Precursors/*metabolism ; Protein Sorting Signals/*metabolism
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  • 4
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-04-27
    Description: Light-dependent expression of rbcS, the gene encoding the small subunit of ribulose-1,5-bisphosphate carboxylase, which is the key enzyme involved in carbon fixation in higher plants, is regulated at the transcriptional level. Sequence analysis of the gene has uncovered a conserved GT motif in the -150 to -100 region of many rbcS promoters. This motif serves as the binding site of a nuclear factor, designated GT-1. Analysis of site-specific mutants of pea rbcS-3A promoter demonstrated that GT-1 binding in vitro is correlated with light-responsive expression of the rbcS promoter in transgenic plants. However, it is not known whether factors other than GT-1 might also be required for activation of transcription by light. A synthetic tetramer of box II (TGTGTGGTTAATATG), the GT-1 binding site located between -152 to -138 of the rbcS-3A promoter, inserted upstream of a truncated cauliflower mosaic virus 35S promoter is sufficient to confer expression in leaves of transgenic tobacco. This expression occurs principally in chloroplast-containing cells, is induced by light, and is correlated with the ability of box II to bind GT-1 in vitro. The data show that the binding site for GT-1 is likely to be a part of the molecular light switch for rbcS activation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lam, E -- Chua, N H -- New York, N.Y. -- Science. 1990 Apr 27;248(4954):471-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Plant Molecular Biology, Rockefeller University, New York, NY 10021.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2330508" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Binding Sites ; Chloramphenicol O-Acetyltransferase/genetics ; Cloning, Molecular ; DNA-Binding Proteins/*metabolism ; Gene Expression Regulation/*physiology ; Genetic Vectors ; *Light ; Molecular Sequence Data ; Mutation ; Nuclear Proteins/*metabolism ; Plant Proteins/*metabolism ; *Plants, Toxic ; Promoter Regions, Genetic/genetics ; Ribulose-Bisphosphate Carboxylase/*genetics ; Tobacco/enzymology/*genetics ; Transcription, Genetic/radiation effects ; Transformation, Genetic
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  • 5
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-02-09
    Description: Transcription of a typical eukaryotic gene by RNA polymerase II is activated by proteins bound to sites found near the beginning of the gene as well as to sites, called enhancers, located a great distance from the gene. According to one view, the primary difference between an activator that can work at a large distance and one that cannot is that the former bears a particularly strong activating region; the stronger the activating region, the more readily the activator interacts with its target bound near the transcriptional start site, with the intervening DNA looping out to accommodate the reaction. One alternative view is that the effect of proteins bound to enhancers might require some special aspect of cellular or chromosome structure. Consistent with the first view, an activator bearing an unusually potent activating region can stimulate transcription of a mammalian gene in a HeLa nuclear extract when bound as far as 1.3 kilobase pairs upstream or 320 base pairs downstream of the transcriptional start site.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Carey, M -- Leatherwood, J -- Ptashne, M -- New York, N.Y. -- Science. 1990 Feb 9;247(4943):710-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Molecular Biology, Harvard University, Cambridge, MA 02138.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2405489" target="_blank"〉PubMed〈/a〉
    Keywords: Activating Transcription Factors ; Binding Sites ; Blood Proteins/pharmacology ; Cloning, Molecular ; DNA/metabolism ; DNA-Binding Proteins ; Fungal Proteins/metabolism/*pharmacology ; HeLa Cells ; Phosphoproteins/pharmacology ; Promoter Regions, Genetic ; RNA Polymerase II/metabolism ; Recombinant Fusion Proteins/pharmacology ; *Saccharomyces cerevisiae Proteins ; Templates, Genetic ; Trans-Activators/pharmacology ; Transcription Factors/pharmacology ; Transcription, Genetic/*drug effects
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  • 6
    Publication Date: 1990-07-27
    Description: The major autophosphorylation sites of the rat beta II isozyme of protein kinase C were identified. The modified threonine and serine residues were found in the amino-terminal peptide, the carboxyl-terminal tail, and the hinge region between the regulatory lipid-binding domain and the catalytic kinase domain. Because this autophosphorylation follows an intrapeptide mechanism, extraordinary flexibility of the protein is necessary to phosphorylate the three regions. Comparison of the sequences surrounding the modified residues showed no obvious recognition motif nor any similarity to substrate phosphorylation sites, suggesting that proximity to the active site may be the primary criterion for their phosphorylation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Flint, A J -- Paladini, R D -- Koshland, D E Jr -- DK09765/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1990 Jul 27;249(4967):408-11.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular and Cellular Biology, University of California, Berkeley 94720.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2377895" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Binding Sites ; Brain/enzymology ; Cloning, Molecular ; Isoenzymes/genetics/*metabolism ; Molecular Sequence Data ; Peptide Fragments/isolation & purification/metabolism ; Phosphorylation ; Protein Conformation ; Protein Kinase C/genetics/*metabolism ; Rats ; Recombinant Proteins/metabolism ; Signal Transduction ; Trypsin
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  • 7
    Publication Date: 1990-11-09
    Description: High sequence selectivity in DNA-protein interactions was analyzed by measuring discrimination by Eco RI endonuclease between the recognition site GAATTC and systematically altered DNA sites. Base analogue substitutions that preserve the sequence-dependent conformational motif of the GAATTC site permit deletion of single sites of protein-base contact at a cost of +1 to +2 kcal/mol. However, the introduction of any one incorrect natural base pair costs +6 to +13 kcal/mol in transition state interaction energy, the resultant of the following interdependent factors: deletion of one or two hydrogen bonds between the protein and a purine base; unfavourable steric apposition between a group on the protein and an incorrectly placed functional group on a base; disruption of a pyrimidine contact with the protein; loss of some crucial interactions between protein and DNA phosphates; and an increased energetic cost of attaining the required DNA conformation in the transition state complex. Eco RI endonuclease thus achieves stringent discrimination by both "direct readout" (protein-base contracts) and "indirect readout" (protein-phosphate contacts and DNA conformation) of the DNA sequence.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lesser, D R -- Kurpiewski, M R -- Jen-Jacobson, L -- GM-29207/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Nov 9;250(4982):776-86.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Sciences, University of Pittsburgh, PA 15260.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2237428" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Base Sequence ; Binding Sites ; DNA/chemistry/genetics/*metabolism ; Deoxyribonuclease EcoRI/chemistry/*metabolism ; Energy Transfer ; Molecular Sequence Data ; Nucleic Acid Conformation ; Phosphates/metabolism ; Substrate Specificity
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  • 8
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-08-17
    Description: A class of transcriptional regulator proteins bind to DNA at dyad-symmetric sites through a motif consisting of (i) a "leucine zipper" sequence that associates into noncovalent, parallel, alpha-helical dimers and (ii) a covalently connected basic region necessary for binding DNA. The basic regions are predicted to be disordered in the absence of DNA and to form alpha helices when bound to DNA. These helices bind in the major groove forming multiple hydrogen-bonded and van der Waals contacts with the nucleotide bases. To test this model, two peptides were designed that were identical to natural leucine zipper proteins only at positions hypothesized to be critical for dimerization and DNA recognition. The peptides form dimers that bind specifically to DNA with their basic regions in alpha-helical conformations.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉O'Neil, K T -- Hoess, R H -- DeGrado, W F -- New York, N.Y. -- Science. 1990 Aug 17;249(4970):774-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Central Research and Development Department, E.I. du Pont de Nemours & Co., Wilmington, DE 19880-0328.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2389143" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Base Sequence ; Binding Sites ; Chemistry, Physical ; Circular Dichroism ; Computer Simulation ; DNA/*metabolism ; DNA-Binding Proteins/*metabolism ; Hydrogen Bonding ; *Leucine ; Macromolecular Substances ; Models, Molecular ; Molecular Sequence Data ; Physicochemical Phenomena ; Protein Conformation
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  • 9
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-10-26
    Description: Expression of the L-arabinose BAD operon in Escherichia coli is regulated by AraC protein which acts both positively in the presence of arabinose to induce transcription and negatively in the absence of arabinose to repress transcription. The repression of the araBAD promoter is mediated by DNA looping between AraC protein bound at two sites near the promoter separated by 210 base pairs, araI and araO2. In vivo and in vitro experiments presented here show that an AraC dimer, with binding to half of araI and to araO2, maintains the repressed state of the operon. The addition of arabinose, which induces the operon, breaks the loop, and shifts the interactions from the distal araO2 site to the previously unoccupied half of the araI site. The conversion between the two states does not require additional binding of AraC protein and appears to be driven largely by properties of the protein rather than being specified by the slightly different DNA sequences of the binding sites. Slight reorientation of the subunits of AraC could specify looping or unlooping by the protein. Such a mechanism could account for regulation of DNA looping in other systems.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lobell, R B -- Schleif, R F -- GM18277/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Oct 26;250(4980):528-32.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Graduate Department of Biochemistry, Brandeis University, Waltham, MA 02254.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2237403" target="_blank"〉PubMed〈/a〉
    Keywords: AraC Transcription Factor ; Arabinose/genetics/pharmacology ; *Bacterial Proteins ; Binding Sites ; *DNA, Bacterial/genetics/metabolism ; DNA, Superhelical/metabolism ; Escherichia coli/*genetics ; Escherichia coli Proteins ; Fucose/pharmacology ; Gene Expression Regulation, Bacterial/*drug effects ; Guanine/metabolism ; Macromolecular Substances ; Methylation ; Mutation ; Nucleic Acid Conformation/*drug effects ; Operon ; Protein Conformation/drug effects ; Repressor Proteins/metabolism/*pharmacology ; *Transcription Factors
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  • 10
    Publication Date: 1990-09-21
    Description: Thyrotropin (TSH), luteinizing hormone (LH), and chorionic gonadotropin (CG) are structurally related glycoprotein hormones, which bind to receptors that share a high degree of sequence similarity. However, comparison of the primary amino acid sequences of the TSH and LH-CG receptors reveals two unique insertions of 8 and 50 amino acids in the extracellular domain of the TSH receptor. The functional significance of these insertions were determined by site-directed mutagenesis. Deletion of the 50-amino acid tract (residues 317 to 366) had no effect on TSH binding or on TSH and thyroid-stimulating immunoglobulin (TSI) biological activities. In contrast, either deletion or substitution of the eight-amino acid region (residues 38 to 45) abolished these activities. This eight-amino acid tract near the amino terminus of the TSH receptor appears to be an important site of interaction for both TSH and TSI.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wadsworth, H L -- Chazenbalk, G D -- Nagayama, Y -- Russo, D -- Rapoport, B -- DK-19289/DK/NIDDK NIH HHS/ -- DK-36182/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1990 Sep 21;249(4975):1423-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Medicine, Veterans Administration Medical Center, San Francisco, CA 94121.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2169649" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Binding Sites ; Cell Line ; Chromosome Deletion ; Clone Cells ; Cyclic AMP/metabolism ; Humans ; Molecular Sequence Data ; Mutation ; Oligonucleotide Probes ; Receptors, Thyrotropin/*genetics/metabolism ; Thyrotropin/*metabolism/pharmacology ; Transfection
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  • 11
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-10-26
    Description: The yeast protein RAP1, initially described as a transcriptional regulator, binds in vitro to sequences found in a number of seemingly unrelated genomic loci. These include the silencers at the transcriptionally repressed mating-type genes, the promoters of many genes important for cell growth, and the poly[(cytosine)1-3 adenine] [poly(C1-3A)] repeats of telomeres. Because RAP1 binds in vitro to the poly(C1-3A) repeats of telomeres, it has been suggested that RAP1 may be involved in telomere function in vivo. In order to test this hypothesis, the telomere tract lengths of yeast strains that contained conditionally lethal (ts) rap1 mutations were analyzed. Several rap1ts alleles reduced telomere length in a temperature-dependent manner. In addition, plasmids that contain small, synthetic telomeres with intact or mutant RAP1 binding sites were tested for their ability to function as substrates for poly(C1-3A) addition in vivo. Mutations in the RAP1 binding sites reduced the efficiency of the addition reaction.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lustig, A J -- Kurtz, S -- Shore, D -- GM 40094/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Oct 26;250(4980):549-53.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology, Memorial Sloan-Kettering Cancer Center, New York, NY 10021.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2237406" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Binding Sites ; Chromosomes, Fungal/metabolism/*ultrastructure ; DNA-Binding Proteins/metabolism ; Fungal Proteins/genetics/*metabolism ; *Genes, Fungal ; *Genes, Mating Type, Fungal ; Molecular Sequence Data ; Mutation ; Plasmids ; Poly A/metabolism ; Poly C/metabolism ; Repetitive Sequences, Nucleic Acid ; Saccharomyces cerevisiae/*genetics ; Temperature ; *Transcription Factors ; Transformation, Genetic
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  • 12
    Publication Date: 1990-07-27
    Description: The enzymatic degradation of cellulose is an important process, both ecologically and commercially. The three-dimensional structure of a cellulase, the enzymatic core of CBHII from the fungus Trichoderma reesei reveals an alpha-beta protein with a fold similar to but different from the widely occurring barrel topology first observed in triose phosphate isomerase. The active site of CBHII is located at the carboxyl-terminal end of a parallel beta barrel, in an enclosed tunnel through which the cellulose threads. Two aspartic acid residues, located in the center of the tunnel are the probable catalytic residues.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rouvinen, J -- Bergfors, T -- Teeri, T -- Knowles, J K -- Jones, T A -- New York, N.Y. -- Science. 1990 Jul 27;249(4967):380-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology, BMC, Uppsala, Sweden.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2377893" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; Cellulose/metabolism ; Cellulose 1,4-beta-Cellobiosidase ; Chemistry, Physical ; Crystallization ; Crystallography ; *Glycoside Hydrolases/metabolism ; Glycosylation ; Hydrogen Bonding ; Hydrogen-Ion Concentration ; Mitosporic Fungi/*enzymology ; Molecular Sequence Data ; Molecular Structure ; Physicochemical Phenomena ; Protein Conformation ; Trichoderma/*enzymology
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  • 13
    Publication Date: 1990-08-31
    Description: The isocitrate dehydrogenase of Escherichia coli is an example of a ubiquitous class of enzymes that are regulated by covalent modification. In the three-dimensional structure of the enzyme-substrate complex, isocitrate forms a hydrogen bond with Ser113, the site of regulatory phosphorylation. The structures of Asp113 and Glu113 mutants, which mimic the inactivation of the enzyme by phosphorylation, show minimal conformational changes from wild type, as in the phosphorylated enzyme. Calculations based on observed structures suggest that the change in electrostatic potential when a negative charge is introduced either by phosporylation or site-directed mutagenesis is sufficient to inactivate the enzyme. Thus, direct interaction at a ligand binding site is an alternative mechanism to induced conformational changes from an allosteric site in the regulation of protein activity by phosphorylation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hurley, J H -- Dean, A M -- Sohl, J L -- Koshland, D E Jr -- Stroud, R M -- GM 24485/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Aug 31;249(4972):1012-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Biophysics, University of California, San Francisco 94143-0448.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2204109" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; Escherichia coli/*enzymology/genetics ; Homeostasis ; Isocitrate Dehydrogenase/genetics/*metabolism ; Models, Molecular ; Molecular Sequence Data ; Phosphorylation ; Protein Conformation
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  • 14
    Publication Date: 1990-03-09
    Description: Comparison of a lambda repressor-operator complex and a 434 repressor-operator complex reveals that three conserved residues in the helix-turn-helix (HTH) region make similar contacts in each of the crystallographically determined structures. These conserved residues and their interactions with phosphodiester oxygens help establish a frame of reference within which other HTH residues make contacts that are critical for site-specific recognition. Such "positioning contacts" may be important conserved features within families of HTH proteins. In contrast, the structural comparisons appear to rule out any simple "recognition code" at the level of detailed side chain-base pair interactions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pabo, C O -- Aggarwal, A K -- Jordan, S R -- Beamer, L J -- Obeysekare, U R -- Harrison, S C -- GM 29109/GM/NIGMS NIH HHS/ -- GM 31471/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Mar 9;247(4947):1210-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2315694" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Asparagine ; Base Composition ; Base Sequence ; Binding Sites ; *DNA-Binding Proteins ; Glutamine ; Hydrogen Bonding ; Molecular Sequence Data ; Molecular Structure ; *Operator Regions, Genetic ; Protein Conformation ; Repressor Proteins/*metabolism ; Transcription Factors/*metabolism ; Viral Proteins ; Viral Regulatory and Accessory Proteins
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  • 15
    Publication Date: 1990-04-06
    Description: A complementary DNA (cDNA) clone that encodes inositol 1,4,5-trisphosphate 3-kinase was isolated from a rat brain cDNA expression library with the use of monoclonal antibodies. This clone had an open reading frame that would direct the synthesis of a protein consisting of 449 amino acids and with a molecular mass of 49,853 daltons. The putative protein revealed a potential calmodulin-binding site and six regions with amino acid compositions (PEST regions) common to proteins that are susceptible to calpain. Expression of the cDNA in COS cells resulted in an approximately 150-fold increase in inositol 1,4,5-trisphosphate 3-kinase activity of these cells.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Choi, K Y -- Kim, H K -- Lee, S Y -- Moon, K H -- Sim, S S -- Kim, J W -- Chung, H K -- Rhee, S G -- New York, N.Y. -- Science. 1990 Apr 6;248(4951):64-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Biochemistry, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2157285" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Binding Sites ; Brain/enzymology ; Calcium/metabolism ; Calmodulin/metabolism ; Calpain/antagonists & inhibitors/pharmacology ; Cell Line ; *Cloning, Molecular ; Codon ; DNA/*genetics ; *Gene Expression ; Molecular Sequence Data ; Molecular Weight ; Phosphotransferases/*genetics/metabolism ; *Phosphotransferases (Alcohol Group Acceptor) ; Plasmids ; Rats ; Transfection
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  • 16
    Publication Date: 1990-07-20
    Description: The crystallographic structure of a recombinant hirudin-thrombin complex has been solved at 2.3 angstrom (A) resolution. Hirudin consists of an NH2-terminal globular domain and a long (39 A) COOH-terminal extended domain. Residues Ile1 to Tyr3 of hirudin form a parallel beta-strand with Ser214 to Glu217 of thrombin with the nitrogen atom of Ile1 making a hydrogen bond with Ser195 O gamma atom of the catalytic site, but the specificity pocket of thrombin is not involved in the interaction. The COOH-terminal segment makes numerous electrostatic interactions with an anion-binding exosite of thrombin, whereas the last five residues are in a helical loop that forms many hydrophobic contacts. In all, 27 of the 65 residues of hirudin have contacts less than 4.0 A with thrombin (10 ion pairs and 23 hydrogen bonds). Such abundant interactions may account for the high affinity and specificity of hirudin.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rydel, T J -- Ravichandran, K G -- Tulinsky, A -- Bode, W -- Huber, R -- Roitsch, C -- Fenton, J W 2nd -- HL13160/HL/NHLBI NIH HHS/ -- HL43229/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1990 Jul 20;249(4966):277-80.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Michigan State University, East Lansing 48824.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2374926" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; Hirudins/*metabolism ; Humans ; Models, Molecular ; Molecular Sequence Data ; Protein Binding ; Protein Conformation ; Recombinant Proteins/metabolism ; Thrombin/*metabolism ; X-Ray Diffraction
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  • 17
    Publication Date: 1990-05-25
    Description: An active site, cofactor-containing peptide has been obtained in high yield from bovine serum amine oxidase. Sequencing of this pentapeptide indicates: Leu-Asn-X-Asp-Tyr. Analysis of the peptide by mass spectrometry, ultraviolet-visible spectroscopy, and proton nuclear magnetic resonance leads to the identification of X as 6-hydroxydopa. This result indicates that, contrary to previous proposals, pyrroloquinoline quinone is not the active site cofactor in mammalian copper amine oxidases. Although 6-hydroxydopa has been implicated in neurotoxicity, the data presented suggest that this compound has a functional role at an enzyme active site.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Janes, S M -- Mu, D -- Wemmer, D -- Smith, A J -- Kaur, S -- Maltby, D -- Burlingame, A L -- Klinman, J P -- GM 39296/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 May 25;248(4958):981-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of California, Berkeley 94720.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2111581" target="_blank"〉PubMed〈/a〉
    Keywords: *Amine Oxidase (Copper-Containing) ; Amino Acid Sequence ; Animals ; Binding Sites ; Cattle ; Copper ; Dihydroxyphenylalanine/*analogs & derivatives/metabolism ; Magnetic Resonance Spectroscopy ; Mass Spectrometry ; Molecular Sequence Data ; Oxidoreductases/metabolism ; Oxidoreductases Acting on CH-NH Group Donors/blood/*metabolism ; Peptide Fragments/analysis/chemical synthesis ; Quinones/metabolism ; Spectrophotometry, Ultraviolet
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  • 18
    Publication Date: 1990-12-21
    Description: Human growth hormone (hGH) elicits a diverse set of biological activities including lactation that derives from binding to the prolactin (PRL) receptor. The binding affinity of hGH for the extracellular binding domain of the hPRL receptor (hPRLbp) was increased about 8000-fold by addition of 50 micromolar ZnCl2. Zinc was not required for binding of hGH to the hGH binding protein (hGHbp) or for binding of hPRL to the hPRLbp. Other divalent metal ions (Ca2+, Mg2+, Cu2+, Mn2+, and Co2+) at physiological concentrations did not support such strong binding. Scatchard analysis indicated a stoichiometry of one Zn2+ per hGH.hPRLbp complex. Mutational analysis showed that a cluster of three residues (His18, His21, and Glu174) in hGH and His188 from the hPRLbp (conserved in all PRL receptors but not GH receptors) are probable Zn2+ ligands. This polypeptide hormone.receptor "zinc sandwich" provides a molecular mechanism to explain why nonprimate GHs are not lactogenic and offers a molecular link between zinc deficiency and its association with altered functions of hGH.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cunningham, B C -- Bass, S -- Fuh, G -- Wells, J A -- New York, N.Y. -- Science. 1990 Dec 21;250(4988):1709-12.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Protein Engineering, Genentech, Inc., South San Francisco, CA 94080.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2270485" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Base Sequence ; Binding Sites ; Chlorides/*pharmacology ; Growth Hormone/*metabolism ; Humans ; Kinetics ; Models, Molecular ; Molecular Sequence Data ; Mutagenesis, Site-Directed ; Oligonucleotide Probes ; Plasmids ; Protein Conformation ; Receptors, Prolactin/drug effects/genetics/*metabolism ; Restriction Mapping ; Zinc/metabolism/*pharmacology ; *Zinc Compounds
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  • 19
    Publication Date: 1990-12-21
    Description: The mechanism by which transcription factors stimulate DNA replication in eukaryotes is unknown. Bovine papillomavirus DNA synthesis requires the products of the viral E1 gene and the transcriptional activator protein encoded by the E2 gene. Experimental data showed that the 68-kilodalton (kD) E1 protein formed a complex with the 48-kD E2 transcription factor. This complex bound specifically to the viral origin of replication, which contains multiple binding sites for E2. Repressor proteins encoded by the E2 open reading frame failed to complex with E1 suggesting that the 162-amino acid region of E2 that participates in transactivation contained critical determinants for interaction with E1. The physical association between a replication protein and a transcription factor suggests that transcriptional activator proteins may function in targeting replication initiator proteins to their respective origins of replication.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mohr, I J -- Clark, R -- Sun, S -- Androphy, E J -- MacPherson, P -- Botchan, M R -- CA-30490/CA/NCI NIH HHS/ -- CA-42414/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1990 Dec 21;250(4988):1694-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular and Cell Biology, University of California, Berkely 94720.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2176744" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Binding Sites ; Bovine papillomavirus 1/*genetics ; Cell Line ; *DNA Replication ; DNA, Viral/biosynthesis/genetics ; DNA-Binding Proteins/*metabolism ; Genes, Viral ; Open Reading Frames ; Protein Binding ; Repressor Proteins/*metabolism ; Transcription Factors/*metabolism ; Viral Proteins/*metabolism
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  • 20
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-08-17
    Description: A recently described class of DNA binding proteins is characterized by the "bZIP" motif, which consists of a basic region that contacts DNA and an adjacent "leucine zipper" that mediates protein dimerization. A peptide model for the basic region of the yeast transcriptional activator GCN4 has been developed in which the leucine zipper has been replaced by a disulfide bond. The 34-residue peptide dimer, but not the reduced monomer, binds DNA with nanomolar affinity at 4 degrees C. DNA binding is sequence-specific as judged by deoxyribonuclease I footprinting. Circular dichroism spectroscopy suggests that the peptide adopts a helical structure when bound to DNA. These results demonstrate directly that the GCN4 basic region is sufficient for sequence-specific DNA binding and suggest that a major function of the GCN4 leucine zipper is simply to mediate protein dimerization. Our approach provides a strategy for the design of short sequence-specific DNA binding peptides.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Talanian, R V -- McKnight, C J -- Kim, P S -- GM13665/GM/NIGMS NIH HHS/ -- GM44162/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Aug 17;249(4970):769-71.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Whitehead Institute for Biomedical Research, Nine Cambridge Center, MA 02142.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2389142" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Base Sequence ; Binding Sites ; Circular Dichroism ; DNA/*metabolism ; DNA-Binding Proteins/*metabolism ; Deoxyribonuclease I ; Disulfides ; Fungal Proteins/*metabolism ; Leucine ; Macromolecular Substances ; Molecular Sequence Data ; Peptides/*metabolism ; Protein Conformation ; *Protein Kinases ; *Saccharomyces cerevisiae Proteins ; Transcription Factors/*metabolism
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  • 21
    Publication Date: 1990-02-23
    Description: Bacterial MerR proteins are dimeric DNA-binding proteins that mediate the Hg(II)-dependent induction of mercury resistance operons. Site-directed mutagenesis of the Bacillus sp. RC607 MerR protein reveals that three of four Cys residues per monomer are required for Hg(II) binding at the single high-affinity binding site. Inactive mutant homodimers can exchange subunits to form heterodimers active for Hg(II) binding. Studies of a heterodimer retaining only three of eight cysteine residues per dimer reveal that Cys79 in one subunit and Cys114 and Cys123 in the second subunit are necessary and sufficient for high-affinity Hg(II) binding in an asymmetric, subunit bridging coordination complex.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Helmann, J D -- Ballard, B T -- Walsh, C T -- GM20011/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Feb 23;247(4945):946-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2305262" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Bacillus/*analysis/genetics ; Bacterial Proteins/genetics/*metabolism ; Base Sequence ; Binding Sites ; Cations ; DNA-Binding Proteins/genetics/*metabolism ; Macromolecular Substances ; Mercury/*metabolism ; Molecular Sequence Data ; Mutation ; Structure-Activity Relationship
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  • 22
    Publication Date: 1990-11-23
    Description: The CD4 antigen is the high affinity cellular receptor for the human immunodeficiency virus type-1 (HIV-1). Binding of recombinant soluble CD4 (sCD4) or the purified V1 domain of sCD4 to the surface glycoprotein gp120 on virions resulted in rapid dissociation of gp120 from its complex with the transmembrane glycoprotein gp41. This may represent the initial stage in virus-cell and cell-cell fusion. Shedding of gp120 from virions induced by sCD4 may also contribute to the mechanism by which these soluble receptor molecules neutralize HIV-1.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Moore, J P -- McKeating, J A -- Weiss, R A -- Sattentau, Q J -- New York, N.Y. -- Science. 1990 Nov 23;250(4984):1139-42.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Chester Beatty Laboratories, Institute of Cancer Research, London, United Kingdom.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2251501" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antibodies, Monoclonal/pharmacology ; Antigens, CD4/immunology/*metabolism ; Binding Sites ; Binding, Competitive ; Cell Line ; Cricetinae ; HIV Envelope Protein gp120/*metabolism ; HIV Envelope Protein gp41/metabolism ; HIV-1/*metabolism ; Virion/*metabolism
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  • 23
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-08-17
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Roberts, L -- New York, N.Y. -- Science. 1990 Aug 17;249(4970):744.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2117777" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; GTPase-Activating Proteins ; Genes, ras ; Humans ; Neurofibromatosis 1/*genetics ; Proteins/genetics ; Sequence Homology, Nucleic Acid ; ras GTPase-Activating Proteins
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  • 24
    Publication Date: 1990-01-05
    Description: Receptor binding studies show that resistance of a laboratory-selected Plodia interpunctella strain to a Bacillus thuringiensis insecticidal crystal protein (ICP) is correlated with a 50-fold reduction in affinity of the membrane receptor for this protein. The strain is sensitive to a second type of ICP that apparently recognizes a different receptor. Understanding the mechanism of resistance will provide strategies to prevent or delay resistance and hence prolong the usefulness of B. thuringiensis ICPs as environmentally safe insecticides.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Van Rie, J -- McGaughey, W H -- Johnson, D E -- Barnett, B D -- Van Mellaert, H -- New York, N.Y. -- Science. 1990 Jan 5;247(4938):72-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Plant Genetic Systems, Gent, Belgium.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2294593" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Bacillus thuringiensis ; *Bacterial Proteins/metabolism ; Bacterial Toxins/metabolism ; Binding Sites ; Cell Membrane/metabolism ; *Endotoxins ; Hemolysin Proteins ; Insecticide Resistance/*physiology ; *Lepidoptera ; Microvilli/metabolism ; *Moths ; *Pest Control, Biological ; Receptors, Drug/metabolism
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  • 25
    Publication Date: 1990-12-14
    Description: A chemical description of the action of phospholipase A2 (PLA2) can now be inferred with confidence from three high-resolution x-ray crystal structures. The first is the structure of the PLA2 from the venom of the Chinese cobra (Naja naja atra) in a complex with a phosphonate transition-state analogue. This enzyme is typical of a large, well-studied homologous family of PLA2S. The second is a similar complex with the evolutionarily distant bee-venom PLA2. The third structure is the uninhibited PLA2 from Chinese cobra venom. Despite the different molecular architectures of the cobra and bee-venom PLA2s, the transition-state analogue interacts in a nearly identical way with the catalytic machinery of both enzymes. The disposition of the fatty-acid side chains suggests a common access route of the substrate from its position in the lipid aggregate to its productive interaction with the active site. Comparison of the cobra-venom complex with the uninhibited enzyme indicates that optimal binding and catalysis at the lipid-water interface is due to facilitated substrate diffusion from the interfacial binding surface to the catalytic site rather than an allosteric change in the enzyme's structure. However, a second bound calcium ion changes its position upon the binding of the transition-state analogue, suggesting a mechanism for augmenting the critical electrophile.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3443688/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3443688/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Scott, D L -- White, S P -- Otwinowski, Z -- Yuan, W -- Gelb, M H -- Sigler, P B -- GM22324/GM/NIGMS NIH HHS/ -- HL36235/HL/NHLBI NIH HHS/ -- R01 HL036235/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1990 Dec 14;250(4987):1541-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2274785" target="_blank"〉PubMed〈/a〉
    Keywords: Bee Venoms/analysis ; Binding Sites ; Calcium/metabolism ; Catalysis ; Chemistry, Physical ; Cobra Venoms/analysis ; Models, Molecular ; Molecular Structure ; Organophosphonates/metabolism ; Phospholipases A/chemistry/*metabolism ; Phospholipases A2 ; Phospholipids/metabolism ; Physicochemical Phenomena ; Protein Conformation ; X-Ray Diffraction
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  • 26
    Publication Date: 1990-12-14
    Description: The 2.0 angstroms crystal structure of a complex containing bee-venom phospholipase A2 (PLA2) and a phosphonate transition-state analogue was solved by multiple isomorphous replacement. The electron-density map is sufficiently detailed to visualize the proximal sugars of the enzyme's N-linked carbohydrate and a single molecule of the transition-state analogue bound ot its active center. Although bee-venom PLA2 does not belong to the large homologous Class I/II family that encompasses most other well-studied PLA2s, there is segmental sequence similarity and conservation of many functional substructures. Comparison of the bee-venom enzyme with other phospholipase structures provides compelling evidence for a common catalytic mechanism.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Scott, D L -- Otwinowski, Z -- Gelb, M H -- Sigler, P B -- GM22324/GM/NIGMS NIH HHS/ -- HL36235/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1990 Dec 14;250(4987):1563-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2274788" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Bee Venoms/*analysis ; Binding Sites ; Calcium/metabolism ; Carbohydrate Metabolism ; Catalysis ; Chemistry, Physical ; Crystallization ; Hydrogen Bonding ; Molecular Sequence Data ; Molecular Structure ; Phosphatidylethanolamines/*metabolism ; Phospholipases A/*chemistry/metabolism ; Phospholipases A2 ; Physicochemical Phenomena ; Protein Conformation
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  • 27
    Publication Date: 1990-03-09
    Description: The T cell antigen receptor (TCR) delta gene is located within the TCR alpha locus. A T cell-specific transcriptional enhancer, distinct from the TCR alpha enhancer, has been identified within the J delta 3-C delta intron of the human T cell receptor delta gene. This enhancer activates transcription from the V delta 1 and V delta 3 promoters as well as from heterologous promoters. Enhancer activity has been localized to a 250-bp region that contains multiple binding sites for nuclear proteins. Thus, transcriptional control of the TCR delta and TCR alpha genes is mediated by distinct regulatory elements.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Redondo, J M -- Hata, S -- Brocklehurst, C -- Krangel, M S -- R01-GM41052/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Mar 9;247(4947):1225-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Tumor Virology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2156339" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Binding Sites ; Cell Line ; Chloramphenicol O-Acetyltransferase/genetics ; DNA Restriction Enzymes ; Deoxyribonuclease I ; Enhancer Elements, Genetic/*genetics ; Gene Rearrangement ; Gene Rearrangement, alpha-Chain T-Cell Antigen Receptor ; Humans ; Molecular Sequence Data ; Mutation ; Nuclear Proteins/metabolism ; Plasmids ; Promoter Regions, Genetic/genetics ; Receptors, Antigen, T-Cell/*genetics ; Repetitive Sequences, Nucleic Acid ; *Transcription, Genetic ; Transfection
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  • 28
    Publication Date: 1990-06-25
    Description: Lipoprotein-associated coagulation inhibitor (LACI) appears to inhibit tissue factor (TF)-induced blood coagulation by forming a quaternary inhibitory complex containing factor Xa, LACI, factor VIIa, and TF. A genetically engineered hybrid protein consisting of the light chain of factor Xa and the first Kunitz-type inhibitor domain of LACI is shown to directly inhibit the activity of the factor VIIa-TF catalytic complex. Unlike inhibition of factor VIIa-TF activity by native LACI, inhibition by the hybrid protein is not dependent on factor Xa. In an assay of TF-induced coagulation, 50% TF inhibition occurs with hybrid protein at 35 nanograms per milliliter, whereas LACI at 2.5 micrograms per milliliter is required for an equivalent effect. gamma-Carboxylation of glutamic acid residues in the factor Xa light chain portion of the hybrid protein is required for inhibitory activity, indicating that the first Kunitz-type domain of LACI alone is not sufficient for inhibition of factor VIIa-TF.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Girard, T J -- MacPhail, L A -- Likert, K M -- Novotny, W F -- Miletich, J P -- Broze, G J Jr -- New York, N.Y. -- Science. 1990 Jun 15;248(4961):1421-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Hematology/Oncology, Jewish Hospital, Washington University Medical Center, St. Louis, MO 63110.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1972598" target="_blank"〉PubMed〈/a〉
    Keywords: 1-Carboxyglutamic Acid/metabolism ; Amino Acid Sequence ; Animals ; Binding Sites ; Calcium/metabolism ; Cell Line ; Cloning, Molecular ; Factor VII/antagonists & inhibitors/metabolism/*pharmacology ; Factor VIIa/*antagonists & inhibitors/metabolism ; Factor Xa/metabolism/*pharmacology ; Fibroblasts/metabolism ; Glutamates/metabolism ; Glutamic Acid ; Lipoproteins/metabolism/*pharmacology ; Mice ; Molecular Sequence Data ; Papillomaviridae ; Protease Inhibitors/*pharmacology ; Protein Sorting Signals ; Recombinant Fusion Proteins/*pharmacology ; Thromboplastin/antagonists & inhibitors/metabolism/*pharmacology ; Transfection
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 29
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-05-25
    Description: The viral protein p6, required for the protein-primed initiation of replication of Bacillus subtilis phage phi 29, forms a nucleoprotein complex at the viral replication origins that shows novel features. Deoxyribonuclease I and hydroxyl radical footprinting data, as well as the induction of positive supercoiling, support a model in which a DNA right-handed superhelix tightly wraps around a multimeric p6 core. The interaction occurs through the DNA minor groove. The activity of p6 not only requires the formation of the complex but also its correct positioning, indicating that the other proteins involved in the initiation of replication recognize, at a precise position, either the p6 core or the DNA conformational change induced by p6.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Serrano, M -- Salas, M -- Hermoso, J M -- 5 R01 GM 27242-10/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 May 25;248(4958):1012-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Centro de Biologia Molecular (CSIC-UAM), Universidad Autonoma, Madrid, Spain.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2111580" target="_blank"〉PubMed〈/a〉
    Keywords: Bacillus subtilis ; Bacteriophages/*genetics ; Base Sequence ; Binding Sites ; *DNA Replication ; DNA, Superhelical/metabolism ; DNA-Binding Proteins/*ultrastructure ; Deoxyribonucleoproteins/*metabolism/ultrastructure ; Molecular Sequence Data ; Nucleic Acid Conformation ; Oligonucleotides ; Viral Proteins/metabolism/ultrastructure ; Virus Replication
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  • 30
    Publication Date: 1990-12-14
    Description: The crystal structure of a complex between a phosphonate transition-state analogue and the phospholipase A2 (PLA2) from Naja naja atra venom has been solved and refined to a resolution of 2.0 angstroms. The identical stereochemistry of the two complexes that comprise the crystal's asymmetric unit indicates both the manner in which the transition state is stabilized and how the hydrophobic fatty acyl chains of the substrate are accommodated by the enzyme during interfacial catalysis. The critical features that suggest the chemistry of binding and catalysis are the same as those seen in the crystal structure of a similar complex formed with the evolutionarily distant bee-venom PLA2.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉White, S P -- Scott, D L -- Otwinowski, Z -- Gelb, M H -- Sigler, P B -- GM22324/GM/NIGMS NIH HHS/ -- HL 36235/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1990 Dec 14;250(4987):1560-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2274787" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Bee Venoms/analysis ; Binding Sites ; Calcium/metabolism ; Catalysis ; Chemistry, Physical ; Cobra Venoms/*analysis ; Crystallization ; Hydrogen Bonding ; Molecular Sequence Data ; Molecular Structure ; Phosphatidylethanolamines/*metabolism ; Phospholipases A/*chemistry/metabolism ; Phospholipases A2 ; Physicochemical Phenomena ; Protein Conformation
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  • 31
    Publication Date: 1990-07-20
    Description: The 70-residue carboxyl-terminal domain of the muscle contractile protein troponin-C contains two helix-loop-helix calcium (Ca)-binding sites that are related to each other by approximate twofold rotational symmetry. Hydrophobic residues from the helices and a short three residue beta sheet at the interface of the two sites act to stabilize the protein domain in the presence of Ca. A synthetic 34-residue peptide representing one of these sites (site III) has been synthesized and studied by H-1 nuclear magnetic resonance (NMR) spectroscopy. In solution this peptide undergoes a Ca-induced conformational change to form the helix-loop-helix Ca-binding motif. Two-dimensional nuclear Overhauser effect spectra have provided evidence for the formation of a beta sheet and interactions between several hydrophobic residues from opposing helices as found in troponin-C. It is proposed that a symmetric two-site dimer similar in tertiary structure to the carboxyl-terminal domain of troponin-C forms from the assembly of two site III peptides in the Ca-bound form.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shaw, G S -- Hodges, R S -- Sykes, B D -- New York, N.Y. -- Science. 1990 Jul 20;249(4966):280-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, University of Alberta, Edmonton, Canada.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2374927" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Binding Sites ; Calcium/*metabolism/pharmacology ; Hydrogen ; Magnetic Resonance Spectroscopy/methods ; Models, Molecular ; Molecular Sequence Data ; Peptides/chemical synthesis/*metabolism ; Protein Conformation ; Troponin/chemical synthesis/*metabolism ; Troponin C ; Turkeys
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  • 32
    Publication Date: 1990-04-27
    Description: The gene encoding the 49-kilodalton protein that undergoes light-induced phosphorylation in the Drosophila photoreceptor has been isolated and characterized. The encoded protein has 401 amino acid residues and a molecular mass of 44,972 daltons, and it shares approximately 42 percent amino acid sequence identity with arrestin (S-antigen), which has been proposed to quench the light-induced cascade of guanosine 3',5'-monophosphate hydrolysis in vertebrate photoreceptors. Unlike the 49-kilodalton protein, however, arrestin, which appears to bind to phosphorylated rhodopsin, has not itself been reported to undergo phosphorylation. In vitro, Ca2+ was the only agent found that would stimulate the phosphorylation of the 49-kilodalton protein. The phosphorylation of this arrestin-like protein in vivo may therefore be triggered by a Ca2+ signal that is likely to be regulated by light-activated phosphoinositide-specific phospholipase C.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yamada, T -- Takeuchi, Y -- Komori, N -- Kobayashi, H -- Sakai, Y -- Hotta, Y -- Matsumoto, H -- EY06595/EY/NEI NIH HHS/ -- New York, N.Y. -- Science. 1990 Apr 27;248(4954):483-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City 73190.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2158671" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; *Antigens ; Arrestin ; Binding Sites ; Calcium/pharmacology ; Cloning, Molecular ; Cyclic GMP/metabolism ; DNA/genetics ; Drosophila melanogaster/*genetics ; Enzyme Activation/drug effects ; *Eye Proteins ; Isoelectric Point ; Molecular Sequence Data ; Molecular Weight ; Mutation ; Phosphatidylinositol Diacylglycerol-Lyase ; *Phosphoproteins/genetics/metabolism ; Phosphoric Diester Hydrolases/metabolism ; Phosphorylation ; Photoreceptor Cells/*analysis ; Protein Biosynthesis ; Restriction Mapping ; Sequence Homology, Nucleic Acid
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  • 33
    Publication Date: 1990-02-23
    Description: Ras proteins participate as a molecular switch in the early steps of the signal transduction pathway that is associated with cell growth and differentiation. When the protein is in its GTP complexed form it is active in signal transduction, whereas it is inactive in its GDP complexed form. A comparison of eight three-dimensional structures of ras proteins in four different crystal lattices, five with a nonhydrolyzable GTP analog and three with GDP, reveals that the "on" and "off" states of the switch are distinguished by conformational differences that span a length of more than 40 A, and are induced by the gamma-phosphate. The most significant differences are localized in two regions: residues 30 to 38 (the switch I region) in the second loop and residues 60 to 76 (the switch II region) consisting of the fourth loop and the short alpha-helix that follows the loop. Both regions are highly exposed and form a continuous strip on the molecular surface most likely to be the recognition sites for the effector and receptor molecule(or molecules). The conformational differences also provide a structural basis for understanding the biological and biochemical changes of the proteins due to oncogenic mutations, autophosphorylation, and GTP hydrolysis, and for understanding the interactions with other proteins.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Milburn, M V -- Tong, L -- deVos, A M -- Brunger, A -- Yamaizumi, Z -- Nishimura, S -- Kim, S H -- CA45593/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1990 Feb 23;247(4945):939-45.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of California, Berkeley.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2406906" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Crystallization ; Crystallography ; Guanosine Diphosphate/metabolism ; Guanosine Triphosphate/metabolism ; Humans ; Models, Molecular ; Molecular Structure ; Protein Conformation ; Proto-Oncogene Proteins/*metabolism ; Proto-Oncogene Proteins p21(ras) ; *Signal Transduction ; Structure-Activity Relationship
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  • 34
    Publication Date: 1990-09-21
    Description: Ribonuclease H digests the RNA strand of duplex RNA.DNA hybrids into oligonucleotides. This activity is indispensable for retroviral infection and is involved in bacterial replication. The ribonuclease H from Escherichia coli is homologous with the retroviral proteins. The crystal structure of the E. coli enzyme reveals a distinctive alpha-beta tertiary fold. Analysis of the molecular model implicates a carboxyl triad in the catalytic mechanism and suggests a likely mode for the binding of RNA.DNA substrates. The structure was determined by the method of multiwavelength anomalous diffraction (MAD) with the use of synchrotron data from a crystal of the recombinant selenomethionyl protein.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yang, W -- Hendrickson, W A -- Crouch, R J -- Satow, Y -- GM 34102/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Sep 21;249(4975):1398-405.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2169648" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; Computer Graphics ; *Endoribonucleases/genetics ; Escherichia coli/enzymology ; Models, Molecular ; Molecular Sequence Data ; Protein Conformation ; Recombinant Proteins ; Ribonuclease H ; *Selenium ; *Selenomethionine ; Sequence Homology, Nucleic Acid ; X-Ray Diffraction/methods
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  • 35
    Publication Date: 1990-08-31
    Description: The isocitrate dehydrogenase of Escherichia coli is regulated by covalent modification at the active site rather than, as expected, at an allosteric site. As a means of evaluating the mechanism of regulation, the kinetics of the substrate, 2R,3S-isocitrate, and a substrate analog, 2R-malate, were compared for the native, phosphorylated, and mutant enzymes. Phosphorylation decreases activity by more than a factor of 10(6) for the true substrate, but causes minor changes in the activity of the substrate analog. The kinetic results indicate that electrostatic repulsion and steric hindrance between the phosphoryl moiety and the gamma carboxyl group of 2R,3S-isocitrate are the major causes of the inactivation, with a lesser contribution from the loss of a hydrogen bond.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Dean, A M -- Koshland, D E Jr -- New York, N.Y. -- Science. 1990 Aug 31;249(4972):1044-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular and Cell Biology, University of California, Berkeley 94720.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2204110" target="_blank"〉PubMed〈/a〉
    Keywords: Allosteric Site ; Amino Acid Sequence ; Binding Sites ; Escherichia coli/*enzymology/genetics ; Isocitrate Dehydrogenase/genetics/*metabolism ; Models, Molecular ; Mutation ; Protein Conformation
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  • 36
    Publication Date: 1990-11-23
    Description: While it has been known for some time that the c-Myc protein binds to random DNA sequences, no sequence-specific binding activity has been detected. At its carboxyl terminus, c-Myc contains a basic--helix-loop-helix (bHLH) motif, which is important for dimerization and specific DNA binding, as demonstrated for other bHLH protein family members. Of those studied, most bHLH proteins bind to sites that contain a CA- -TG consensus. In this study, the technique of selected and amplified binding-sequence (SAAB) imprinting was used to identify a DNA sequence that was recognized by c-Myc. A purified carboxyl-terminal fragment of human c-Myc that contained the bHLH domain bound in vitro in a sequence-specific manner to the sequence, CACGTG. These results suggest that some of the biological functions of Myc family proteins are accomplished by sequence-specific DNA binding that is mediated by the carboxyl-terminal region of the protein.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Blackwell, T K -- Kretzner, L -- Blackwood, E M -- Eisenman, R N -- Weintraub, H -- R01 CA20525/CA/NCI NIH HHS/ -- T32 CA09437/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1990 Nov 23;250(4984):1149-51.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98104.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2251503" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Binding Sites ; DNA/*metabolism ; Glutathione Transferase ; Leucine Zippers ; Macromolecular Substances ; Molecular Sequence Data ; Oligonucleotides/metabolism ; Polymerase Chain Reaction ; Protein Conformation ; Proto-Oncogene Proteins c-myc/*metabolism ; Recombinant Fusion Proteins/metabolism ; Templates, Genetic
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  • 37
    Publication Date: 1990-11-23
    Description: A technique was developed for studying protein-DNA recognition that can be applied to any purified protein, partially purified protein, or cloned gene. From oligonucleotides in which particular positions are of random sequence, that subset to which a given protein binds is amplified by the polymerase chain reaction and sequenced as a pool. These selected and amplified binding site (SAAB) "imprints" provide a characteristic set of preferred sequences for protein binding. With this technique, it was shown that homo- and heterooligomers of the helix-loop-helix proteins MyoD and E2A recognize a common consensus sequence, CA--TG, but otherwise bind to flanking and internal positions with different sequence preferences that suggest half-site recognition. These findings suggest that different combinations of dimeric proteins can have different binding sequence preferences.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Blackwell, T K -- Weintraub, H -- New York, N.Y. -- Science. 1990 Nov 23;250(4984):1104-10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Genetics, Fred Hutchinson Cancer Research Center, Seattle, WA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2174572" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Binding Sites ; DNA/*metabolism ; DNA-Binding Proteins/*metabolism ; Glutathione Transferase ; Macromolecular Substances ; Molecular Sequence Data ; Muscle Proteins/*metabolism ; MyoD Protein ; Oligonucleotides/metabolism ; Polymerase Chain Reaction ; Protein Conformation ; Recombinant Fusion Proteins/metabolism ; Repetitive Sequences, Nucleic Acid ; TCF Transcription Factors ; Templates, Genetic ; Transcription Factor 7-Like 1 Protein ; *Transcription Factors
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  • 38
    Publication Date: 1990-11-30
    Description: The Wilms' tumor locus (WTL) at 11p13 contains a gene that encodes a zinc finger-containing protein that has characteristics of a DNA-binding protein. However, binding of this protein to DNA in a sequence-specific manner has not been demonstrated. A synthetic gene was constructed that contained the zinc finger region, and the protein was expressed in Escherichia coli. The recombinant protein was used to identify a specific DNA binding site from a pool of degenerate oligonucleotides. The binding sites obtained were similar to the sequence recognized by the early growth response-1 (EGR-1) gene product, a zinc finger-containing protein that is induced by mitogenic stimuli. A mutation in the zinc finger region of the protein originally identified in a Wilms' tumor patient abolished its DNA-binding activity. These results suggest that the WTL protein may act at the DNA binding site of a growth factor-inducible gene and that loss of DNA-binding activity contributes to the tumorigenic process.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rauscher, F J 3rd -- Morris, J F -- Tournay, O E -- Cook, D M -- Curran, T -- CA0917-15/CA/NCI NIH HHS/ -- CA10817/CA/NCI NIH HHS/ -- CA23413/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1990 Nov 30;250(4985):1259-62.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Wistar Institute, Philadelphia, PA 19104.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2244209" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Base Sequence ; Binding Sites ; Binding, Competitive ; Chromosomes, Human, Pair 11 ; Consensus Sequence ; DNA/genetics/*metabolism ; DNA-Binding Proteins/genetics/*metabolism ; Early Growth Response Protein 1 ; Escherichia coli/genetics ; *Genes, Wilms Tumor ; Humans ; *Immediate-Early Proteins ; Molecular Sequence Data ; Mutation ; Oligonucleotides/metabolism ; Polymerase Chain Reaction ; Recombinant Proteins/metabolism ; Restriction Mapping ; Transcription Factors/genetics/*metabolism ; *Zinc Fingers/genetics
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  • 39
    Publication Date: 1990-08-03
    Description: A two-fold (C2) symmetric inhibitor of the protease of human immunodeficiency virus type-1 (HIV-1) has been designed on the basis of the three-dimensional symmetry of the enzyme active site. The symmetric molecule inhibited both protease activity and acute HIV-1 infection in vitro, was at least 10,000-fold more potent against HIV-1 protease than against related enzymes, and appeared to be stable to degradative enzymes. The 2.8 angstrom crystal structure of the inhibitor-enzyme complex demonstrated that the inhibitor binds to the enzyme in a highly symmetric fashion.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Erickson, J -- Neidhart, D J -- VanDrie, J -- Kempf, D J -- Wang, X C -- Norbeck, D W -- Plattner, J J -- Rittenhouse, J W -- Turon, M -- Wideburg, N -- AI 27220/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 1990 Aug 3;249(4968):527-33.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Computer-Assisted Molecular Design, Abbott Laboratories, Abbott Park, IL 60064.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2200122" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; Drug Design ; Endopeptidases/*metabolism ; Gene Products, pol/*metabolism ; HIV Protease ; HIV-1/*enzymology ; Kinetics ; Models, Molecular ; Molecular Sequence Data ; Protease Inhibitors/*pharmacology ; Protein Conformation ; Sugar Alcohols/*pharmacology ; Valine/*analogs & derivatives/pharmacology
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  • 40
    Publication Date: 1990-01-26
    Description: Activity of the immunoglobulin heavy and kappa light chain gene enhancers depends on a complex interplay of ubiquitous and developmentally regulated proteins. Two complementary DNAs were isolated that encode proteins, denoted ITF-1 and ITF-2, that are expressed in a variety of cell types and bind the microE5/kappa 2 motif found in both heavy and kappa light chain enhancers. The complementary DNAs are the products of distinct genes, yet both ITF-1 and ITF-2 are structurally and functionally similar. The two proteins interact with one another through their putative helix-loop-helix motifs and each possesses a distinct domain that dictates transcription activation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Henthorn, P -- Kiledjian, M -- Kadesch, T -- New York, N.Y. -- Science. 1990 Jan 26;247(4941):467-70.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Philadelphia, PA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2105528" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; B-Lymphocytes/metabolism ; Base Sequence ; Binding Sites ; Cell Line ; Cloning, Molecular ; DNA/genetics/*metabolism ; *Enhancer Elements, Genetic ; *Genes, Immunoglobulin ; Humans ; Immunoglobulin kappa-Chains/genetics ; Immunoglobulin mu-Chains/genetics ; Macromolecular Substances ; Mice ; Molecular Sequence Data ; Plasmids ; Protein Conformation ; Saccharomyces cerevisiae/genetics ; Transcription Factors/*metabolism ; Transcription, Genetic ; Transfection ; Transformation, Genetic
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  • 41
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-12-14
    Description: The neurotransmitter acetylcholine (ACh) is bound with 50-micromolar affinity by a completely synthetic receptor (host) comprising primarily aromatic rings. The host provided an overall hydrophobic binding site, but one that could recognize the positive charge of the quaternary ammonium group of ACh through a stabilizing interaction with the electron-rich pi systems of the aromatic rings (cation-pi interaction). Similar interactions may be involved in biological recognition of ACh and other choline derivatives.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Dougherty, D A -- Stauffer, D A -- GM36356/GM/NIGMS NIH HHS/ -- GM43936/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Dec 14;250(4987):1558-60.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Arnold and Mabel Beckman Laboratories of Chemical Synthesis, California Institute of Technology, Pasadena 91125.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2274786" target="_blank"〉PubMed〈/a〉
    Keywords: Acetylcholine/*metabolism ; Affinity Labels ; Amino Acid Sequence ; Animals ; Binding Sites ; Cations ; Drosophila ; Electrochemistry ; Immunoglobulin Fab Fragments/metabolism ; *Models, Molecular ; Molecular Sequence Data ; Molecular Structure ; Phosphorylcholine/metabolism ; Quaternary Ammonium Compounds/*metabolism ; Receptors, Cholinergic/chemistry/*metabolism ; Thermodynamics ; Torpedo
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  • 42
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1990-05-18
    Description: The NH2-terminal locations of a dimer containing the DNA binding domain of the yeast transcriptional activator GCN4 have been mapped on the binding sites 5'-CTGACTAAT-3' and 5'-ATGACTCTT-3'. Affinity cleaving was effected by synthetic GCN4 proteins with Fe.EDTA moieties at the NH2-terminus. Analysis of the DNA cleavage patterns for dimers of the Fe.EDTA-proteins corresponding to GCN4 residues 222 to 281 and 226 to 281 revealed that the NH2-termini were in the major groove nine to ten base pairs apart and were symmetrically displaced four to five base pairs from the central C of the recognition site. This result is consistent with the Y-shaped scissor grip-leucine zipper model recently proposed for a class of DNA binding proteins important in the regulation of gene expression.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Oakley, M G -- Dervan, P B -- New York, N.Y. -- Science. 1990 May 18;248(4957):847-50.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena 91125.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2111578" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Base Sequence ; Binding Sites ; DNA/*metabolism ; *DNA-Binding Proteins ; Edetic Acid/metabolism ; Ferric Compounds/metabolism ; Fungal Proteins/*metabolism ; Leucine ; Macromolecular Substances ; Molecular Sequence Data ; Molecular Structure ; *Protein Kinases ; *Saccharomyces cerevisiae Proteins ; Transcription Factors/*metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 43
    Publication Date: 1990-01-05
    Description: Incubation of a 90-kilodalton ferritin repressor protein (FRP), either free or complexed with an L-ferritin transcript, with hemin or Co3+-protoporphyrin IX prevented subsequent repression of ferritin synthesis in a wheat germ extract. Neither FeCl3 in combinations with H2O2, nor Fe3+ or Fe2+ chelated with EDTA, nor Zn2+-protoporphyrin IX, nor protoporphyrin IX caused significant inactivation of FRP. FRP that had been inactivated by hemin remained chemically intact, as revealed by SDS-polyacrylamide gel electrophoresis. Inclusion of chelators of iron or free radical scavengers did not alter the inactivation produced by hemin. These and other results indicate that hemin derepresses ferritin synthesis in vitro.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lin, J J -- Daniels-McQueen, S -- Patino, M M -- Gaffield, L -- Walden, W E -- Thach, R E -- AI 20484/AI/NIAID NIH HHS/ -- RR 5369/RR/NCRR NIH HHS/ -- New York, N.Y. -- Science. 1990 Jan 5;247(4938):74-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Washington University, St. Louis, MO 63130.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2294594" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Binding, Competitive ; Electrophoresis, Polyacrylamide Gel ; Ferritins/biosynthesis/*genetics ; Free Radicals ; Heme/*analogs & derivatives ; Hemin/*pharmacology ; Iron Chelating Agents/pharmacology ; Protein Biosynthesis/*drug effects ; Protoporphyrins/metabolism ; RNA, Messenger/*genetics ; Repressor Proteins/*genetics/metabolism ; Transcription Factors/*genetics
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
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  • 44
    Publication Date: 1990-03-30
    Description: Several mutants derived from transformed human B cell lines are defective in expressing major histocompatibility complex (MHC) class II genes. The failure to express a class II gene in at least one such mutant line has been mapped to the MHC class II X box, a conserved transcriptional element in the promoter region. A complementary DNA encoding a DNA-binding protein (human X box binding protein, hXBP-1) whose target is the human DR alpha X box and the 3' flanking region has now been cloned. This complementary DNA encoded a protein with structural similarities to the c-jun proto-oncogene product, and its target sequence was closely related to the palindromic target sequence of c-jun. Mutation of the hXBP-1 DNA target sequence decreased DR alpha promoter activity in vivo. These studies suggest that the hXBP-1 protein acts as a transcription factor in B cells.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Liou, H C -- Boothby, M R -- Finn, P W -- Davidon, R -- Nabavi, N -- Zeleznik-Le, N J -- Ting, J P -- Glimcher, L H -- CA42771-01/CA/NCI NIH HHS/ -- GM36864/GM/NIGMS NIH HHS/ -- R01-CA48185/CA/NCI NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1990 Mar 30;247(4950):1581-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Cancer Biology, Harvard School of Public Health, Boston, MA 02115.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2321018" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; B-Lymphocytes ; Base Sequence ; Binding Sites ; Cell Line, Transformed ; DNA/*genetics ; DNA-Binding Proteins/*genetics/metabolism ; HLA-DR Antigens/*genetics/metabolism ; Humans ; Leucine ; Molecular Sequence Data ; Mutation ; *Promoter Regions, Genetic ; Transcription Factors/*genetics/metabolism ; Transfection
    Print ISSN: 0036-8075
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  • 45
    Publication Date: 1990-08-24
    Description: The ligand-binding function of integrin adhesion receptors depends on divalent cations. A mutant alpha IIb beta 3 integrin (platelet gpIIb/IIIa) that lacks ligand recognition shows immunologic evidence of a perturbed interaction with divalent cations. This was found to be caused by a G----T mutation that resulted in an Asp119----Tyr119 substitution in the beta 3 subunit. This residue is proximal to bound ligand and is in a conserved region among integrins that are enriched in oxygenated residues. The spacing of these residues aligns with the calcium-binding residues in EF hand proteins, suggesting interaction with receptor-bound divalent cation as a mechanism of ligand binding common to all integrins.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Loftus, J C -- O'Toole, T E -- Plow, E F -- Glass, A -- Frelinger, A L 3rd -- Ginsberg, M H -- AR 27214/AR/NIAMS NIH HHS/ -- HL 28235/HL/NHLBI NIH HHS/ -- HL 42977/HL/NHLBI NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1990 Aug 24;249(4971):915-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Committee on Vascular Biology, Research Institute of Scripps Clinic, La Jolla, CA 92037.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2392682" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Aspartic Acid ; Base Sequence ; Binding Sites ; Cell Line ; Integrins/*genetics/metabolism ; Ligands ; Macromolecular Substances ; Molecular Sequence Data ; *Mutation ; Oligonucleotide Probes ; Platelet Membrane Glycoproteins/*genetics/metabolism ; Polymerase Chain Reaction ; Protein Conformation ; Sequence Homology, Nucleic Acid ; Tyrosine
    Print ISSN: 0036-8075
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  • 46
    Publication Date: 1990-05-18
    Description: The immunosuppressive agents cyclosporin A and FK506 inhibit the transcription of early T cell activation genes. The binding proteins for cyclosporin A and FK506, cyclophilin and FKBP, respectively, are peptidyl-prolyl-cis-trans isomerases, or rotamases. One proposed mechanism for rotamase catalysis by cyclophilin involves a tetrahedral adduct of an amide carbonyl and an enzyme-bound nucleophile. The potent FKBP rotamase inhibitor FK506 has a highly electrophilic carbonyl that is adjacent to an acyl-pipicolinyl (homoprolyl) amide bond. Such a functional group would be expected to form a stabilized, enzyme-bound tetrahedral adduct. Spectroscopic and chemical evidence reveals that the drug interacts noncovalently with its receptor, suggesting that the alpha-keto amid of FK506 serves as a surrogate for the twisted amide of a bound peptide substrate.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rosen, M K -- Standaert, R F -- Galat, A -- Nakatsuka, M -- Schreiber, S L -- GM-38627/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 May 18;248(4957):863-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Harvard University, Cambridge, MA 02138.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1693013" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Isomerases/*antagonists & inhibitors ; Anti-Bacterial Agents/metabolism/*pharmacology ; Binding Sites ; Carrier Proteins/antagonists & inhibitors/metabolism ; Chemical Phenomena ; Chemistry ; Cloning, Molecular ; Cyclosporins/metabolism/pharmacology ; Escherichia coli/genetics ; Gene Expression ; *Immunosuppressive Agents ; Lymphocyte Activation ; Magnetic Resonance Spectroscopy ; Molecular Structure ; Peptidylprolyl Isomerase ; Recombinant Proteins ; T-Lymphocytes/immunology ; Tacrolimus
    Print ISSN: 0036-8075
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  • 47
    Publication Date: 1990-09-21
    Description: Triosephosphate isomerase (TIM) is used as a model system for the study of how a localized conformational change in a protein structure is produced and related to enzyme reactivity. An 11-residue loop region moves more than 7 angstroms and closes over the active site when substrate binds. The loop acts like a "lid" in that it moves rigidly and is attached by two hinges to the remainder of the protein. The nature of the motion appears to be built into the loop by conserved residues; the hinge regions, in contrast, are not conserved. Results of molecular dynamics calculations confirm the structural analysis and suggest a possible ligand-induced mechanism for loop closure.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Joseph, D -- Petsko, G A -- Karplus, M -- New York, N.Y. -- Science. 1990 Sep 21;249(4975):1425-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Massachusetts Institute of Technology, Cambridge 02139.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2402636" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; Carbohydrate Epimerases/*metabolism ; Hydrogen Bonding ; Models, Molecular ; Molecular Sequence Data ; Protein Binding ; *Protein Conformation ; Software ; Triose-Phosphate Isomerase/*metabolism
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  • 48
    Publication Date: 1990-04-27
    Description: The nitrogen regulatory protein NtrC of enteric bacteria activates transcription of the glnA gene by catalyzing isomerization of closed complexes between RNA polymerase and the glnA promoter to open complexes. NtrC binds to sites upstream of glnA that have properties of eukaryotic transcriptional enhancers. NtrC-binding sites were found to facilitate open complex formation when these sites and the glnA promoter were located on different rings of a singly linked catenane, but not when the two rings were decatenated. The results provide evidence that NtrC contacts RNA polymerase-promoter complexes in a process mediated by formation of a DNA loop. NtrC-binding sites serve to tether NtrC near the glnA promoter, thereby increasing the frequency of collisions between NtrC and polymerase-promoter complexes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wedel, A -- Weiss, D S -- Popham, D -- Droge, P -- Kustu, S -- GM 38361/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Apr 27;248(4954):486-90.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Plant Pathology, University of California, Berkeley 94720.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1970441" target="_blank"〉PubMed〈/a〉
    Keywords: Bacterial Proteins/*metabolism ; Binding Sites ; DNA Transposable Elements ; DNA, Bacterial/metabolism ; DNA, Superhelical/metabolism ; DNA-Binding Proteins/*metabolism ; DNA-Directed RNA Polymerases/metabolism ; *Enhancer Elements, Genetic ; Glutamate-Ammonia Ligase/*genetics ; Nucleotidyltransferases/metabolism ; PII Nitrogen Regulatory Proteins ; Plasmids ; *Promoter Regions, Genetic ; Templates, Genetic ; *Trans-Activators ; *Transcription Factors ; *Transcription, Genetic ; Transposases
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  • 49
    Publication Date: 1990-04-06
    Description: Native human plasminogen has a radius of gyration of 39 angstroms. Upon occupation of a weak lysine binding site, the radius of gyration increases to 56 angstroms, an extremely large ligand-induced conformational change. There are no intermediate conformational states between the closed and open form. The conformational chang is not accompanied by a change in secondary structure, hence the closed conformation is formed by interaction between domains that is abolished upon conversion to the open form. This reversible change in conformation, in which the shape of the protein changes from that best described by a prolate ellipsoid to a flexible structure best described by a Debye random coil, is physiologically relevant because a weak lysine binding site regulates the activation of plasminogen.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mangel, W F -- Lin, B H -- Ramakrishnan, V -- New York, N.Y. -- Science. 1990 Apr 6;248(4951):69-73.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Biology Department, Brookhaven National Laboratory, Upton, NY 11973.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2108500" target="_blank"〉PubMed〈/a〉
    Keywords: Aminocaproic Acid/metabolism/pharmacology ; Binding Sites ; Chemistry, Physical ; Circular Dichroism ; Deuterium ; Humans ; Lysine/metabolism ; Neutrons ; Physicochemical Phenomena ; *Plasminogen/metabolism ; Plasminogen Activators/pharmacology ; Protein Conformation/drug effects ; Scattering, Radiation ; Urokinase-Type Plasminogen Activator/pharmacology ; Water
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 50
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 11 (1990) 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
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  • 51
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    Journal of Computational Chemistry 11 (1990), S. 1-18 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Counterpoise corrected ab initio calculations are reported for (H2O)2 and H2O-H2CO. Geometry searches were done in the moment-optimized basis DZP' at the SCF, MP2, and CEPA-1 levels of theory, followed by more accurate single-point calculations in basis ESPB, which includes bondfunctions to saturate the dispersion energy. The final equilibrium binding energies obtained are -4.7 ±0.3 kcal/mol for a near-linear (H2O)2 structure and -4.6 ±0.3 kcal/mol for a strongly bent HOH ‥ OCH2 structure. The energy difference between these systems is much smaller than in all previous ab initio work. Cyclic (C2h) and bifurcated (C2v) transition structures for (H2O)2 are located at 1.0 ±0.1 kcal/mol and 1.9 ±0.3 kcal/mol above the global minimum, respectively. A new partitioning scheme is presented that rigorously partitions the MP2 correlation interaction energy in intra and intermolecular (dispersion) contributions. These terms are large (up to 2 kcal/mol) but of opposite sign for most geometries studied and hence their overall effect upon the final structures is relatively small. The relative merits of the MP2 and CEPA-1 approaches are discussed are discussed and it is concluded that for economical reasons MP2 is to be preferred, especially for larger systems.
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  • 52
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    Journal of Computational Chemistry 11 (1990), S. 45-57 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A data compression method is presented that is generally applicable to first-order convergent iterative procedures that employ subspace expansions or extrapolations based on successive correction vectors. This method is based on the truncation of insignificant information in successive correction vectors. Although the correction vectors themselves may be severely truncated with the proposed approach, the final solution vector may be represented to arbitrary accuracy. A feature of the proposed method is that more slowly convergent iterative procedures allow the correction vectors to be more severely truncated without affecting the overall convergence rate. The method is implemented and applied to the iterative Davidson diagonalization method. If the compressed representation of the expansion vectors can be held in main computer memory, then a significant reduction in the I/O requirements is achieved.
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  • 53
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    Journal of Computational Chemistry 11 (1990), S. 67-75 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: By examining the displacement coordinate metric three modes of constrained optimization for large molecules and clusters are suggested. The first method corresponds to a conventional optimization using internal coordinates. The second mode has applications with respect to both internal and cartesian coordinates. The final mode is particularly interesting because it can result in computational savings. A mixture of both internal and cartesian coordinates is specified where these coordinates are usually a subset of the molecules or clusters total coordinate set. In the optimization only a subset of the energy derivatives need be evaluated reducing the computational effort associated with the gradient calculation.
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  • 54
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    Journal of Computational Chemistry 11 (1990), S. 82-87 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A finite-field method for the calculation of polarizabilities and hyperpolarizabilities is developed based on both an energy expansion and a dipole moment expansion. This procedure is implemented in the MOPAC semiempirical program. Values and components of the dipole moment (μ), polarizability (α), first hyperpolarizability (β), and second hyperpolarizability (γ) are calculated as an extension of the usual MOPAC run. Applications to benzene and substituted benzenes are shown as test cases utilizing both MNDO and AM1 Hamiltonians.
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  • 55
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    Journal of Computational Chemistry 11 (1990), S. 121-151 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A procedure has been developed for global energy minimization of surface loops of proteins in the presence of a fixed core. The ECEPP potential function has been modified to allow more accurate representations of hydrogen bond interactions and intrinsic torsional energies. A computationally efficient representation of hydration free energy has been introduced. A local minimization procedure has been developed that uses a cutoff distance, minimization with respect to subsets of degrees of freedom, analytical second derivatives, and distance constraints between rigid segments to achieve efficiency in applications to surface loops. Efficient procedures have been developed for deforming segments of the initial backbone structure and for removing overlaps. Global energy minimization of a surface loop is accomplished by generating a sequence (or a trajectory) of local minima, the component steps of which are generated by searching collections of local minima obtained by deforming seven-residue segments of the surface loop. The search at each component step consists of the following calculations: (1) A large collection of backbone structures is generated by deforming a seven-residue segment of the initial backbone structure. (2) A collection of low-energy backbone structures is generated by applying local energy minimization to the resulting collection of backbone structures (interactions involving side chains that will be searched in this component step are not included in the energy). (3) One low-energy side-chain structure is generated for each of the resulting low-energy backbone structures. (4) A collection of low-energy local minima is generated by applying local energy minimization to the resulting collection of structures. (5) The local minimum with the lowest energy is retained as the next point of the trajectory. Applications of our global search procedure to surface segments of bovine pancreatic trypsin inhibitor (BPTI) and bovine trypsin suggest that component-step searches are reasonably complete. The computational efficiency of component-step searches is such that trajectories consisting of about 10 component steps are feasible using an FPS-5200 array processor. Our procedure for global energy minimization of surface loops is being used to identify and correct problems with the potential function and to calculate protein structure using a combination of sequence homology and global energy minimization.
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  • 56
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    Journal of Computational Chemistry 11 (1990), S. 416-430 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A systematic analysis of the molecular electrostatic potential (MEP) is presented. This study has been performed with a twofold purpose: first, to study the MEP dependence with regard to the quality of the basis set used to compute the ab initio SCF wavefunction and second, to develop and to assess a new strategy for computing isoelectrostatic potential maps using the semiempirical MNDO wavefunction. The only differences between this procedure and the ab initio SCF MEP computation lie in the freezing of the inner electrons and in the origin of the first-order density matrix. The statistical analysis of MEPs computed for a large number of molecules from MNDO wavefunction and ab initio SCF wavefunctions obtained using STO-3G, 4-31G, 6-31G, 4-31G*, 6-31G*, and 6-31G** basis sets points out the ability of any wavefunction to reproduce the general topological characteristics of the MEP surfaces. Nevertheless, split-valence basis sets including polarization functions are necessary to obtain accurate MEP minimum energy values. MNDO wavefunction tends to overestimate the MEP minima depth by a constant factor and shows an excellent ability to reflect the relative variation of MEP minima energies derived from a rather sophisticated (6-31G*) basis set, lacking of the shortcomings detected in the semiempirical CNDO approximation.
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  • 57
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    Journal of Computational Chemistry 11 (1990), S. 487-492 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Expressions are derived for computing the kinetic energy of a peptide with fixed geometry, in terms of dihedral angles as generalized coordinates; other expressions required for the solution of Lagrange's equations are also presented. The peptide is regarded as held stationary at one end. We also outline the computations that are needed in calculating the components of the third derivative of a potential energy function that consists of a sum of pairwise interatomic interactions.
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  • 58
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    Journal of Computational Chemistry 11 (1990), S. 819-828 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Complexes of alkali and alkaline earth cations with organic compounds are modeled by describing ionligand interaction energies with pair potentials and intraligand as well as interligand energies with the MM2 potential. New pair potentials for the interaction of Li+, Na+, K+, Mg2+, and Ca2+ ions are derived on the basis of 30,000 ab initio interaction energy values with 70 selected model ligand molecules. Various problems of the combination of these two basically different potentials are discussed. An application for the K+ complex of 18-crown-6 is presented. For more flexible ligands the introduction of three-body correction terms of the pair potentials seems necessary.
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  • 59
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    Journal of Computational Chemistry 11 (1990), S. 924-929 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The geometry, electronic structure, and photoelectron spectra of Sb2 and Sb4 have been investigated employing the LCGTO-MP-LSD method. For both molecules the geometrical and spectroscopic constants computed using the VWN potential are in very good agreement with the available experimental data. The HeI photoelectron spectra were computed with different potentials (Xα, GL, HL, BH, and VWN). The calculated spectra are in excellent agreement with the experimental ones and the use of the VWN potential gives the most accurate results. The reliable results for molecules complement those for the Sb atom and show that the proposed LSD Model Potential is able to give an accurate description of the structural and spectroscopic properties of the title molecules.
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  • 60
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    Journal of Computational Chemistry 11 (1990), S. 958-971 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Intermolecular potential functions have been developed for use in computer simulations of alkyl ethers. The simple OPLS model was adopted and parameterized to yield good descriptions of bimolecular and ion-molecule complexes as well as to reproduce experimental thermodynamic properties of liquid ethers. The principal testing featured Monte Carlo statistical mechanics simulations for liquid dimethyl ether (DME), ethyl methyl ether (EME), diethyl ether (DEE), and tetrahydrofuran (THF). Average errors of 1-3% are obtained for the computed densities and heats of vaporization including results for THF at pressures up to 5000 atm. The torsional motion about the central C—O bonds in EME and DEE was included in the simulations using rotational potential functions fit to results of molecular mechanics (MM2) calculations. The liquid-state environment is found to have negligible effect on the conformational equilibria.
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  • 61
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    Journal of Computational Chemistry 11 (1990), S. 972-977 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A quadrature-point-driven implementation of the standard Rys polynomial method for computing two-electron repulsion integrals of gaussian basis functions has been found to be both concise and openended with respect to the angular momentum of the gaussian functions (i.e., s,p,d,f,g,…). These are important features in certain applications, such as molecular properties and property gradients.
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  • 62
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    Journal of Computational Chemistry 11 (1990), S. 994-1002 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Free energy perturbation calculations were performed to determine the free energy of binding associated with the presence of perhaps an unusual hydroxyl group in the transition state analog of nebularine, an inhibitor of the enzyme adenosine deaminase. The presence of a single hydroxyl group in this inhibitor has been found to contribute -9.8 kcal/mol to the free energy of binding, with a 108-fold increase in the binding affinity by the enzyme. In this work, we calculate the difference in solvation free energy for the 1,6-dihydropurine complex versus that of the 6-hydroxyl-1,6-dihydropurine complex to determine if this marked increase in binding affinity is attributed to an unusually hydrophobic hydroxyl group. The calculated ΔG associated for the solvation free energy is -11.8 kcal/mol. This large change in the solvation free energy suggests that this hydroxyl is instead unusually hydrophilic and that the difference in free energy of interaction for the two inhibitors to the enzyme must be at least ca. 20 kcal/mol. Although the crystal structure for adenosine deaminase is currently not known, we attempt to mimic the nature of the active site by constructing models which simulate the enzyme-inhibitor complex. We present a first attempt at determining the change in free energy of binding for a system in which structural data for the enzyme is incomplete. To do this, we construct what we believe is a minimal model of the binding between adenosine deaminase and an inhibitor. The active site is simulated as a single charged carboxyl group which can form a hydrogen bond with the hydroxyl group of the analog. Two different carboxyl anion models are used. In the first model, the association is modeled between an acetic acid anion and the modified inhibitor. The second model consists of a hydrophobic amino acid pocket with an interior Glu residue in the active site. From these models we calculate the change in free energy of association and the overall change in free energy of binding. We calculate the free energies of interaction both in the absence and presence of water. We conclude from this that the presence of a single suitably placed-CO-2 group probably cannot explain the binding effect of the-OH group and that additional interactions will be found in the adenosine deaminase active site.
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  • 63
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    Journal of Computational Chemistry 11 (1990), S. 1029-1037 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Pseudopotentials and valence basis sets to be used in calculations for organometallic compounds of zinc and magnesium have been tested in calculations for the M(CH3)n (M = Zn, Mg; n = 1,2) molecules. Valence correlation effects are treated at the SDCI and CEPA levels. The capability of a polarization potential on zinc to account for the valence shell contracting effect of core valence correlation is studied. Properties considered are geometries, force constants, Mulliken populations, ionization potentials, atomization, and binding energies. Differences in bonding between the two dimethyl compounds are discussed.
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  • 64
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    Journal of Computational Chemistry 11 (1990), S. 1094-1100 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The acid-catalyzed hydrolysis mechanisms of maleamic (4-amino-4-oxo-2-butenoic) acids were studied using AM1 method. The reaction proceeded mainly in two steps: (1) nucleophilic attack of the undissociated carboxyl group on the adjacent aminocarbonyl carbon via a zwitterionic intermediate; and (2) the rate-determining proton transfer to form the zwitterionic tetrahedral intermediate. In each step, the hydration of water and hydronium ion molecules was important in stabilizing the polarized intermediates. The substituent effects at the amide moiety and the 2,3-positions of the maleamic acids were qualitatively estimated for each step.
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  • 65
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    Journal of Computational Chemistry 11 (1990) 
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
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  • 66
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    Journal of Computational Chemistry 11 (1990), S. 1139-1146 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A prescription for applying the method of molecular similarity calculations based on electrostatic potentials and fields is developed by consideration of a typical structure-activity series. Firm conclusions are drawn about the nature of the grid of points surrounding the molecules and about the choice of geometry, but options for point charges are less clearcut.
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    Journal of Computational Chemistry 11 (1990), S. 899-908 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: An expanded form of the Wiener number is suggested for characterization of molecular graphs and structure-property correlations. The simple, computer-oriented method for counting of the novel index is briefly discussed.
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  • 68
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    Journal of Computational Chemistry 11 (1990), S. 1193-1205 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A common requirement in conformational analysis is the identification of a molecule's lowest energy conformations. The application of the A* algorithm to this problem is examined. The algorithm uses heuristic information about the problem domain to direct the search and has been implemented in a system for performing automated conformational analysis. The method is detailed and sample results presented. Some limitations of the approach are identified.
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  • 69
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    Journal of Computational Chemistry 11 (1990), S. 1009-1016 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Heats of formation and net atomic charges of some 120 structures involving substituted phenols, anilines, and benzoic acids and the corresponding anions were calculated by MNDO, AM1, and PM3 semiempirical methods. The gas phase acidities of substituted phenols and anilines and the net atomic charges on the anionic heteroatoms of the corresponding anions have been successfully correlated with σ- constants. Moreover, good correlations with σ were found for the charges on the acidic hydrogens of substituted phenols and anilines. In contrast, the gas phase acidities of substituted benzoic acids and the charges on the anionic oxygens of the corresponding anions are better correlated with Taft σ° constants. Comparisons of these results with experimental data and ab initio theoretical calculations indicate that AM1 and PM3 methods are much better than MNDO in predicting the acidity of aromatic compounds.
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  • 70
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    Journal of Computational Chemistry 11 (1990), S. 1038-1046 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We studied geometries and energies of complexes between water and neutral or protonated imidazole by ab initio molecular orbital calculations using the 4-31G basis set with and without the counterpoise correction. Positions of hydration sites and relative binding energies could be also estimated by using the electrostatic field map of imidazole as calculated by our bond increment method. The reliability of the calculations is confirmed by comparing the geometries of the imidazole-water complex to the experimental ones from the Cambridge Structural Database. These were obtained by X-ray diffraction studies on crystals with water bound to a molecule containing the imidazole fragment.
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  • 71
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    Journal of Computational Chemistry 11 (1990), S. 1061-1071 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A new method for the evaluation of metal complexes with molecular mechanics calculations is described. The method has been employed to determine the global minimum energy conformations of three seven-coordinate lanthanide complexes. The method searches the potential energy surface of the metal complexes for the global minimum structure using the recently reported Random Incremental Pulse Search (RIPS). The molecular mechanics calculations were performed using the MM2 metal-extended force field (MM2MX). This force field excludes 1-3 bending terms about the metal center and, instead, explicitly includes 1-3 nonbonded van der Waals interactions. This affords a model based mainly on steric interactions about the ligating atoms, and removes the necessity of specifying ligand-metal-ligand bond angles for seven-coordinate and higher metal complexes in which no preferred bond angle can be proficiently determined. The calculated minimum-energy structures were well known seven-coordinate conformations in all cases, and a comparison with X-ray crystallographic is presented.
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    Journal of Computational Chemistry 11 (1990), S. 1076-1079 
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The method of approximation of the frozen molecular fragment (FMF) we derived has been applied to calculations of proton affinities. Results are in good agreement with experimental data and extended basis set calculations.
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  • 73
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    Journal of Computational Chemistry 11 (1990), S. 1087-1093 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Myelin basic protein (MBP) is the major extrinsic protein of the myelin sheath in the central nervous system. It is this protein that is destroyed in such demyelinating diseases as multiple sclerosis. We have examined the predicted structures of one segment of MBP using the molecular mechanics program ECEPP83 developed by Scheraga and co-workers as modified by Chuman, Momany, and Schafer. We have focused upon a segment, 87-118, containing the Pro-Pro-Pro sequence (residues 100-102), which has been predicted from standard algorithms to exist in a hairpin loop connecting anti-parallel beta-strands. Several local energy minima have been found and reported. Tripoline sequences are not rare in proteins, but their structure and function is still uncertain.
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    Journal of Computational Chemistry 11 (1990), S. 1101-1110 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Two new computational methods for the evaluation and partitioning of projected, planar, and averaged slab electron densities, implemented in the program PRODEN, are presented. The new algorithms for the projection, demarcation, and integration of electron densities are described and evaluated in terms of speed and numerical accuracy. Integrated Projected Populations are analyzed and some of the advantages and limitations of the methods are discussed.
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  • 75
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    Journal of Computational Chemistry 11 (1990), S. 930-942 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The effect of the addition of diffuse functions of sp type on the first row atoms (and/or of d type on phosphorus) to a MINI-1 minimal basis set is evaluated by comparing the SCF description of the interaction energy and its decomposition, counterpoise (CP) corrected and uncorrected for basis set superposition errors (BSSEs), with that produced by extended basis sets (6-31G** and 3-21G+) as well as by basis sets (6-31G** + VPS and (2d)S), previously successfully tested, designed to minimize the BSSE. The systems considered are a few anions (F-, HCOO-, H2PO-4) H-bonded to water; the basis set performance on a different geometry (bifurcated instead of linear) of the phosphate-water adduct was also considered. An additional comparison with the interaction energy in a neutral dimer, (HF)2, was carried out. The addition of diffuse functions to the MINI-1 basis set, instead of resorting to extended basis sets, seems to be a sensible choice for anions. The equilibrium distance is shifted towards the reference basis set value at the CP corrected level as well as at the uncorrected one. The spread of the energy due to the basis set is hardly distinguishable when the CP corrected values are plotted. The description of the interaction energy in dimers involving phosphorus is improved using d type diffuse functions.
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    Journal of Computational Chemistry 11 (1990) 
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
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    Journal of Computational Chemistry 11 (1990), S. 1017-1020 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Ab initio CI calculations using pseudopotentials to describe germanium inner electrons are carried out on the low-lying excited singlet states (T2) of GeH4. A theoretical analysis of these states in terms of Mulliken population of Rydberg orbitals for each state and oscillator strengths allow us to reinterpret its experimental Vacuum UV electronic spectrum.
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    Journal of Computational Chemistry 11 (1990), S. 1047-1060 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The algorithm used by the program GEPOL to compute the Molecular Surface (MS), as defined by Richards, is presented in detail. GEPOL starts like other algorithms from a set of spheres with van der Waals radii, centered on the atoms or group of atoms of the molecule. GEPOL computes the MS by first searching the spaces inaccessible to the solvent and consequently filling them with a new set of spheres. Here we study the behavior of the method with its parameters, presenting several examples of application.
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    Journal of Computational Chemistry 11 (1990), S. 1080-1086 
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A boundary element method is developed to compute the electrostatic potential inside and around molecules in an electrolyte solution. A set of boundary integral equations are derived based on the integral formulations of the Poisson equation and the linearized Poisson-Boltzmann equation. The boundary integral equations are then solved numerically after discretizing the molecular surface into a number of flat triangular elements. The method is applied to a spherical molecule for which analytical solutions are available. Use is made of both constant and linearly varying unknowns over the boundary elements, and the method is tested for various values of parameters such as the dielectric constant of the molecule, ionic strength, and the location of the interior point charge. The use of the boundary integral method incorporating the nonlinear Poisson-Boltzmann equation is also briefly discussed.
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    Journal of Computational Chemistry 11 (1990), S. 105-111 
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A universal computational approach for evaluating integrals over gaussian basis functions for general operators of the form \documentclass{article}\pagestyle{empty}\begin{document}$$x^{k_x } y^{k_y } z^{k_z } \{ (\frac{\partial }{{\partial x'}})^{l_x } (\frac{\partial }{{\partial y'}})^{l_y } (\frac{\partial }{{\partial z'}})^{l_z } \frac{1}{{r'}}\} (\frac{\partial }{{\partial x}})^{m_x } (\frac{\partial }{{\partial y}})^{m_y } (\frac{\partial }{{\partial z'}})^{m_z } x^{n_x } y^{n_y } z^{n_z }$$\end{document} is presented. The implementation is open-ended with respect to the types of basis functions (s, p, d, f, g, h…) and with respect to the integers that specify the operator. These one-electron integrals comprise operators associated with electrical and magnetic properties of molecules and include those needed to find multipole polarizabilities, multipole susceptibilities, chemical shifts, and so on. The scheme also generates the usual kinetic, nuclear attraction, and overlap operators.
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    Journal of Computational Chemistry 11 (1990), S. 181-193 
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A general computational scheme for the rational design of chiral stationary phases for the chromatographic separation of enantiomers has been established. The developed scheme was based on applying different interaction models (force field methods versus semi empirical quantum chemical methods), different docking algorithms (systematic grid search methods versus interactive methods guided by rules based on binding modes) and different levels of approximations (rigid versus flexible docking) to a representative test problem containing the 3,5-dinitrobenzoyl group. The computational methods in use covered the most sophisticated methods which could presently be applied to problems of such a size (about 80 atoms). It has been shown that the current computational approaches using rigid body approximations for the docked molecules and simple molecular mechanics (not taking pi-“effects” into account) are invalid in view of the required predictive precision of about 1-2 Kcal/mole for the differential binding energy. Another surprising result was the failure of the commonly used systematic search methods in determining the most favorable binding modes. Based on our calculations on the representative test problem we propose a new arrangement for the most stable complexes without parallel stacking of the aromatic pi-donor and the 3,5-dinitrobenzoyl pi-acceptor systems.
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    Journal of Computational Chemistry 11 (1990), S. 223-235 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A novel efficient computer-oriented approach, based on the DAST (dualist angle-restricted spanning tree) code, is introduced for enumeration and generation of planar polyhex hydrocarbons. It is much faster than other approaches in the literature. The numbers of planar polyhex hydrocarbons with 14 hexagons are reported for the first time.
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    Journal of Computational Chemistry 11 (1990), S. 242-248 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Variations of a procedure have been examined for minimization of the energies, calculated using MM2, of two docked molecules. After doing the intramolecular minimization of the individual molecules, randomized orientations of the rigid molecules were brought together to form complexes and the nonbonded energies of interaction were then minimized. Next, pairs having energies within 4.0 kcal/mol of the most stable pair were minimized further by atom-by-atom relaxation of the complex. Only two repetitions of the last two steps were found to give values within 0.001 kcal/mol in more than 90% of the cases. Compared to two other variations of the procedure, this method appeared to avoid erroneous (local, not global) minima. Finally, this overall procedure was tested against chromatographic data in the literature. Using only the most stable comformer of each species, the results appeared to be in qualitative agreement with fractionation data for enantiomeric aminoethanes on a chiral packing very similar to the one modeled here.
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    Journal of Computational Chemistry 11 (1990), S. 249-264 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Structural optimizations of the apically substituted isomer of PH4O- and the diapically substituted isomer of PH3FO- with diffuse-function augmented 3-21G* basis sets and with the 6-31 + G* and 6-31 + + G* basis sets result in P-η4-coordination in these anions. The structures obtained are those of a hydride or fluoride ion “solvated” by or complexed with phosphine oxide, rather than phosphoranes. In contrast, 3-21G* basis sets without diffuse functions on the atom in the trans-apical position with regard to the oxy-substituent yield P-η5-phosphorane structures that appear to be computational artifacts of the small basis set; the formation of the P-η4-geometries is curtailed by the insufficient functional description of the potential trans-apical nucleophilic leaving group. The overall neutral apical isomers of PH4O- · E(E = Li+, NH4+), the diapical isomer of PH3FO-Li+, as well as the model-solvated apical isomer of PH4O- · HF favor P-η5-phosphorane geometries at all of these computational levels. The mechanism by which the E-group alters the electronic structures within PH4Oa- is discussed based on the geometries, the molecular orbitals, and electron density analysis techniques.
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    Journal of Computational Chemistry 11 (1990), S. 291-296 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The adsorption of methane, ethane, propane, n-butane, ethylene, propene, 1-butene, 1,3-butadiene, acetylene, benzene, toluene, naphthalene, anthracene, and pyrene on the basal plane of graphite has been studied by means of a semiempirical method proposed by Fraga based on a 1/R expansion of atom-atom pair potentials. The energies of interaction obtained agree reasonably well with experimental data and statistical calculations. The orientation of the adsorbed molecules relative to the graphite surface rendered by Fraga's method improves the picture provided by other calculations with empirical potentials. These results display Fraga's method as an economical alternative for the study of physisorption of hydrocarbons on the graphite surface.
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    Journal of Computational Chemistry 11 (1990), S. 311-313 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A common approximation used in ab initio molecular orbital calculations assumes that the changes in energy due to use of a larger basis set (as in the inclusion of polarization orbitals) and to allowance for electron correlation are additives. Thus, small basis sets may be used for correlated ab initio calculations, resulting in a great savings in time. While this approach has been shown to perform acceptably in some cases, a systematic study has not been published. We examined 35 species and computed the heats of reaction for 15 processes at the 6-31G level of theory using polarization and correlation correction up to the MP4 level. The same items were then treated by an additive procedure to attain the same level of theory. We also examined the conrotrary ring opening of cyclobutene. Our results indicate that the errors do cancel to some extent but that the uncertainty associated with open shell species is significantly larger than closed shell systems. This calls into question the use of the procedure in predicting the properties of transition states.
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    Journal of Computational Chemistry 11 (1990), S. 336-345 
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Simplified formulas for first and second derivatives of the internal coordinates with respect to Cartesian coordinates are reported for linear and out-of-plane bending motion. They are expressed in a local coordinate system and then rotated to a space-fixed Cartesian coordinate system. For linear motion the important points are: (1) the invariance of the energy with respect to translational and rotational coordinate transformations and (2) the presentation of derivatives of the energy in terms of (α - π)2 rather than (α - π), where α is the bond angle, to avoid indeterminant forms. By factoring the second derivatives of the energy with respect to (α - π) and sinα, analysis in this local coordinate system avoids division by sinα as α → π. The formulas describe linear systems without the need to project the motion onto two perpendicular planes. When the angle is exactly π two degenerate directions arise, and the coordinate axes perpendicular to the axis of the linear sequence of atoms may be chosen arbitrarily. Further refinements and clarifications of methods reported previously to obtain matrix elements for linear and out-of-plane motion are presented.
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    Journal of Computational Chemistry 11 (1990), S. 382-395 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The coefficients in power series, in the variable time, describing coupled nonlinear chemical reactions are easily obtained from a recursion relation. Since these series have a limited radius of convergence they are not very useful as such. If the series are inverted to give time as a function of the appropriate power of a progress variable, the new series converge over the entire time course of the reaction. If, further, the long-time asymptotic behavior, obtained from the linearized kinetic equations, is used, one can obtain a series expansion for a function that describes the correct short-time behavior. This function can be estimated very well using truncated series. The method works well for consecutive nonlinear reactions where the progress variables are monotonic functions of time; this includes many cases where the concentrations of intermediate species go through a maximum as the reaction progresses.
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  • 89
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 11 (1990), S. 401-409 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The accurate calculation of forces from finite difference potentials is very important, especially in the area of Brownian dynamics simulations. Test charge methods are typically used to calculate these forces. In these methods, the potential is calculated with one group of charges present, then the force on a second set of charges is calculated as the negative of the gradient of the potential times the charge. The test charge methods for calculating forces between solute molecules have been compared with more accurate methods and then regions of validity of the test charge methods explored. The test charge methods neglect certain reaction field effects. It is found for the simple charged systems studied that beyond a center-to-center separation of about twice the sum of the molecular radii the test charge approximations can be quite good. For polar molecules with no net charges, however, the corrections can be significant to even longer ranges.
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  • 90
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 11 (1990), S. 431-439 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: It is demonstrated that semiempirical methods give electrostatic potential (ESP) derived atomic point charges that are in reasonable agreement with ab initio ESP charges. Furthermore, we find that MNDO ESP charges are superior to AM1 ESP charges in correlating with ESP charges derived from the 6-31G* basis set. Thus, it is possible to obtain 6-31G* quality point charges by simply scaling MNDO ESP charges. The charges are scaled in a linear (y = Mx) manner to conserve charge. In this way researchers desiring to carry out force field simulations or minimizations can obtain charges by using MNDO, which requires much less computer time than the corresponding 6-31G* calculation.
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  • 91
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    Journal of Computational Chemistry 11 (1990), S. 468-486 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A new algorithm is presented for performing molecular dynamics simulations of peptides with fixed geometry, with the aim of simulating conformational changes and of exploring conformational space. The principle of the method is to expand the potential energy as a Taylor's series in the coordinates around the current point, retaining the force and its first two derivatives, and obtain a series solution of the resulting differential equations using a method due to Lyapunov. By choosing the time step so that the second term in the series is small compared to the first, the true solution can in principle be approximated to any desired degree of accuracy. The algorithm has been used to solve numerically Lagrange's equations of motion for N-acetyl alanine amide and N-acetyl methionide amide, regarded as fixed at their C-termini, under the influence of the ECEPP/2 potential energy function, and time steps of 15-30 fsec have been achieved with little variation in the total energy. Possible directions for future development are discussed.
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  • 92
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    Journal of Computational Chemistry 11 (1990), S. 314-325 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We have undertaken an energy minimization study of the binding of a small ligand, water, to amino acid side-chains. These calculations have been performed on a Meiko Computing surface containing a small number of transputers and on a larger transputer array installed at Edinburgh University. The aim of this study is twofold. First, we wished to compare these potential energy maps for a given side-chain as a function of the local secondary structure and also of the neighboring residue types. Secondly, the energy maps are found to be in good agreement with experimental distributions on the binding of water molecules to amino acid side-chains. The use of our in-house Meiko computing surface increases the speed of these calculations by a factor of about 25 over a VAX 11/750. With larger arrays of transputers, such as that at Edinburgh “concurrent” Supercomputer Project, we achieve increases in speed of over 200 such that these energy maps can be calculated at interactive speeds.
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  • 93
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    Journal of Computational Chemistry 11 (1990), S. 493-510 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A new approach based on computation of the molecular surface interactions (MSI) to estimate several physical properties of pure organic substances is described. MSI are derived from molecular structural data and consist of total molecular surface area, electrostatic molecular surface interactions, and a hydrogen bonding term. This new approach estimates the critical temperature and the molar critical volume of pure organic substances with molecular weights in the range of 40-500 a.u‥ In addition, the following properties can be calculated: the critical pressure, the boiling temperature, the molar volume in liquid state at normal pressure and temperature. The method can be used to predict physical properties of compounds having flexible or rigid, symmetric or asymmetric, polar or nonpolar molecular structures, and compounds with or without hydrogen bonding groups.
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  • 94
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    Journal of Computational Chemistry 11 (1990), S. 524-530 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The reaction mechanisms of the alkaline hydrolysis of N-methylcarbamates were studied using the AM1 method by assuming two possible pathways: (1) nucleophilic attack of hydroxide ion on the carbonyl carbon to give a tetrahedral complex followed by its breakdown to carbamic acid (BAC2); and (2) proton abstraction by hydroxide ion at the nitrogen atom followed by elimination of the alkoxide ion to form N-methyl isocyanate (E1cB). Reaction coordinate analysis showed that the reaction mechanism is determined by both the stability of an intermediate and the energy barrier for elimination.
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  • 95
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    Journal of Computational Chemistry 11 (1990), S. 541-542 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A reparameterized version (PM3) of AM1 has recently been reported and the results for several hundred molecules compared with those from AM1 itself. The comparison implied that PM3 represents a significant improvement over the earlier treatment. The apparently poor performance of AM1 is, however, due to the inclusion of “AM1 results” for elements (A1,P,S) for which AM1 parameters were unavailable. If these are omitted, PM3 is seen to be only marginally better than AM1. Since this conclusion refers only to a specific set of stable molecules, it is not clear whether even this small improvement will apply to other species or studies of reactions. It is in any case insufficient to justify the confusion caused by the release of the new treatment.
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  • 96
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    Journal of Computational Chemistry 11 (1990), S. 545-547 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: An algorithm based on a small matrix approach to the solution of a system of inhomogeneous linear algebraic equations is developed and tested in this short communication. The solution is assumed to lie in an initial subspace and the dimension of the subspace is augmented iteratively by adding the component of the correction vector obtained from the Jacobi scheme on the coefficient matrix A (ATA, if the matrix A is nondefinite) that is orthogonal to the subspace. If the dimension of the subspace becomes inconveniently large, the iterative scheme can be restarted. The scheme is applicable to both symmetric and nonsymmetric matrices. The small matrix is symmetric (nonsymmetric), if the coefficient matrix is symmetric (nonsymmetric). The scheme has rapid convergence even for large nonsymmetric sparse systems.
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  • 97
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    Journal of Computational Chemistry 11 (1990), S. 573-575 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Entropy and solvent effects are calculated for some conformations of Ala-Gly. The inclusion of these effects in energy calculations show the βII type structure to be the most stable.
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  • 98
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 11 (1990), S. 603-622 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A new method is presented for defining a smooth, triangulated analytic surface for biological molecules. The surface produced by the algorithm is well-suited for use with a recently developed polarizationcharge technique1 for the computation of the electrostatic potential of solvated molecules, and may also be used for calculations of molecular surface areas and volumes. The new method employs Connolly's definitions of contact, reentrant and saddle surface,2 but includes modifications that preclude the presence of self-interesting reentrant surface, and also insure a rigorous decomposition of contact regions into curvilinear finite elements. The triangulation algorithm may be used in conjunction with the electrostatic methods described previously to compute the electric potential of molecules of arbitrary shape in solution. Applications include the estimation of hydration enthalpies, computation of the electrostatic forces associated with solvation, estimation of interactions between separate charged species in solution, and computation of the three-dimensional form of the molecular electric potential. Test calculations are presented for a double-stranded dinucleotide, the polypeptide enkephalin, and the protein ferredoxin.
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  • 99
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    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 11 (1990), S. 765-790 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The anomeric effect of the functional groups X = C≡N, C≡CH, COOH, COO-, O—CH3, NH2, and NH+3 has been studied with ab initio techniques. Geometry effects upon rotation around the central C—O bond in X—CH2—O—CH3 have been compared in the various compounds. The energy differences between the conformers with a gauche and trans (X—C—O—C) arrangement were calculated at the 6-31G* level in the fully optimized 4-21G geometries. Energy differences calculated at the 4-21G level appeared not to be reliable, especially for the groups X that contain non-sp3 hybridized atoms. The 6-31G* energy differences indicate a normal anomeric effect for X = COO-, O—CH3, and NH2(g+) (ca. 13 kJ/mol) and a small anomeric effect for X = COOH, C≡N, and C≡CH (ca. 6 kJ/mol). For X = NH2(t) and NH+3 a reverse anomeric effect occurs. These observations are in line with experimental results and evidence is given for a competition among various stereoelectronic interactions that occur at the same anomeric center. Geometry variations can be understood in terms of simple rules associated with anomeric orbital interactions. Trends followed when the group X is varied cannot be related in a straightforward way to the energy differences between the trans and the gauche forms in these compounds. Only the variation in the gauche torsion angle X—C—O—C follows roughly the same trend.
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  • 100
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    Journal of Computational Chemistry 11 (1990), S. 829-836 
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A computer program is developed to compute distance polynomials of graphs containing up to 200 vertices. The code also computes the eigenvalues and the eigenvectors of the distance matrix. It requires as input only the neighborhood information from which the program constructs the distance matrix. The eigenvalues and eigenvectors are computed using the Givens-Householder method while the characteristic polynomials of the distance matrix are constructed using the codes developed by the author before. The newly developed codes are tested out on many graphs containing large numbers of vertices. It is shown that some cyclic isospectral graphs are differentiated by their distance polynomials although distance polynomials themselves are in general not unique structural invariants.
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