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  • 1
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    Antibody to spermine: a natural biological constituent (1980)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1980-06-06
    Description: A protein that binds spermine specifically was separated from normal rabbit serum by affinity chromatography. Immunoelectrophoresis, the Ouchterlony immunodiffusion test, and gradient gel electrophoresis indicated that this protein has immunoglobulin characteristics and consists of several populations of antibodies to spermine. These were sequentially released from Sepharose-spermine gel by step-wise elution with solutions ranging in pH from 4 to 1. The binding constants varied from 5.0 x 10(8) to 11.1 x 10(8) liters per mole. These globulins did not react with monoacetylputrescine, L-ornithine, L-lysine, and histamine. Negligible cross-reactivity was detected with spermidine, putrescine, N8-monoacetylspermidine, cadaverine, and diaminopropane. Since perturbations in polyamine metabolism have been identified in several diseases, the study of extracellular polyamine homeostasis may reveal an important regulatory function for this protein.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bartos, D -- Bartos, F -- Campbell, R A -- Grettie, D P -- Smejtek, P -- New York, N.Y. -- Science. 1980 Jun 6;208(4448):1178-81.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7375929" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antibodies/*isolation & purification ; Binding Sites, Antibody ; Chromatography, Affinity ; Homeostasis ; Immunoglobulin G/isolation & purification ; Kinetics ; Rabbits ; Spermine/*immunology/metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
    Electronic Resource
    Electronic Resource
    Kinetics of alkaline chloramine-T oxidation of arginine monohydrochloride with and without catalytic action of Cu(II) ion (1980)
    Springer
    Monatshefte für Chemie 111 (1980), S. 649-656 
    Details
    ISSN: 1434-4475
    Keywords: Arginine ; Catalysis ; Kinetics ; Mechanism ; Oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Oxidation erfolgt sowohl mit als auch ohne Cu(II)-Katalysator in erster Ordnung bezüglich des Oxidationsmittels und des Substrats; inverse Ordnung wird bezüglich der Alkalikonzentration beobachtet. Bis zu einer Cu(II)-Konzentration von≤2×10−5 M ist die Geschwindigkeitskonstante der Katalysatorkonzentration proportional; darüber wird eine konstantbleibende Geschwindigkeit beobachtet, die nun von der Cu(II)-Konzentration unabhängig ist. Neutralsalze haben keinen Effekt auf die Geschwindigkeitskonstante. Es wird für den katalysierten und unkatalysierten Reaktionsablauf ein Mechanismus vorgeschlagen und ein mathematischer Ansatz präsentiert.
    Notes: Abstract The kinetics of uncatalysed and Cu(II) catalysed oxidation of arginine monohydrochloride was investigated. Both reactions follow a singular order dependence each in oxidant and substrate. An inverse order dependence is reported with the alkali concentration. A plot of observed rate constant versus Cu(II) concentrations Cu(II)≤2.0×10−5 M is linear; from the intercept the rate constant for the uncatalysed pathway was calculated. However, at high copper ion concentrations i.e. Cu(II)〉2.0×10−5 M a fixed value of rate constant was found for all catalyst concentrations. Added neutral salts show an insignificant effect on the reaction rate. Mechanisms were proposed for both cases and rate expressions were derived by applying steady state assumptions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00903319
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  • 3
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of oxidation of quinol by mercuric nitrate inAcOH-H2O-HNO3 medium (1984)
    Springer
    Monatshefte für Chemie 115 (1984), S. 405-414 
    Details
    ISSN: 1434-4475
    Keywords: Kinetics ; Mechanism ; Oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wurde die Kinetik der Oxidation von Chinol mit Quecksilbernitrat in Gegenwart einer Mischung ausAcOH-H2O-HNO3 untersucht, um die aktive Species bei der Oxidation in diesem Medium aufzuklären. Die Reaktionsordnung ist sowohl bezüglich des Chinols als auch des Hg(II)-Ions erster Ordnung. Die Reaktionsgeschwindigkeit erhöht sich leicht mit der HNO3-Konzentration und auch mit abfallender Dielektrizitätskonstante des Mediums. Die Reaktionsgeschwindigkeit sinkt mit dem Zusatz von KNO3. Es ist keinerlei Hinweis auf eine Komplexbildung zwischen Chinol und Hg(II) festzustellen. Die Resultate der Untersuchungen legen HgNO + 3 als aktive Spezies nahe. Es wird ein möglicher Mechanismus mit einem Zweielektronen-Transfer im geschwindigkeitsbestimmenden Schritt vorgeschlagen. Das dabei produziertep-Benzochinon existiert nicht in freier Form, sondern es bildet einen stabilen 1 : 1-Komplex mit Quecksilbernitrat; dieser Komplex wurde mittels TLC und IR charakterisiert.
    Notes: Abstract The kinetics of oxidation of quinol by mercuric nitrate in presence ofAcOH-H2O-HNO3 mixture has been investigated in order to find the active species of mercuric nitrate involved in the oxidation in this medium. The order of reaction both with respect to quinol and Hg(II) is found to be one. The reaction rate slightly increases with the increase in [HNO3] and the decrease of the dielectric constant of the medium. The reaction rate retards on addition of KNO3. There is no evidence for complex formation between quinol and Hg(II). These results suggest that HgNO + 3 might be the active species in this medium. A probable mechanism involving a two electron transfer in the rate determining step has been suggested. The producedp-benzoquinone does not exist in free state but forms a stable (1 : 1) complex with mercuric nitrate which has been characterized by TLC and IR studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00810000
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  • 4
    Electronic Resource
    Electronic Resource
    Mechanistic studies on the electrohydrodimerization of benzylidenemalononitriles (1984)
    Springer
    Monatshefte für Chemie 115 (1984), S. 697-704 
    Details
    ISSN: 1434-4475
    Keywords: Electrohydrodimerization ; Benzylidenemalononitriles ; Kinetics ; Electrohydrodimerization ; Benzylidenemalononitriles ; Kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Mittels derivativer cyclischer Voltammetrie wurden für die Titelreaktion Geschwindigkeitskonstanten und Aktivierungsparameter erhalten (Dimethylformamid als Lösungsmittel). Benzyliden-,p-Methyl- undp-Methoxybenzylidenmalonnitril reagieren ausschließlich über die Dimerisierung ihrer Anionenradikale (Radikal-Radikal-Kopplung), währenddessen die Dimerisierung vonp-Fluorbenzylidenmalonnitril zu 25% über die Kopplung des Anionenradikals mit dem Substrat erfolgt.
    Notes: Abstract Rate constants and activation parameters for the reductive dimerization of substituted benzylidenemalononitriles were obtained from derivate cyclic voltammetry measurements in dimethylformamide as solvent. Benzylidene-,p-methyl-andp-methoxybenzylidenemalononitrile react exclusively via dimerization of their anion radicals (radical-radical coupling) while forp-fluorobenzylidenemalononitrile 25% of the dimerization proceeds by coupling of the anion radical with the substrate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01120964
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  • 5
    Electronic Resource
    Electronic Resource
    Adsorption of molecules of biological interest onto hydroxyapatite (1984)
    Springer
    Calcified tissue international 36 (1984), S. 48-59 
    Details
    ISSN: 1432-0827
    Keywords: Salivary proteins ; Adsorption ; Thermodynamics ; Kinetics ; Hydroxyapatite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Equilibrium and kinetic experiments were conducted to investigate the factors determining the adsorption of salivary macromolecules onto hydroxyapatite. Using amino acids and other small adsorbates, it was determined that the carboxyl attached to the α carbon does not appear to adsorb onto HA and the affinities of side-chain carboxyls are much smaller than that of the phosphate group (phosphoserine). Hydroxyl (serine) displays an extremely high affinity, but its adsorption site on HA is different and the number of such sites is much smaller than found for the rest of the functional groups investigated. It is shown that the information obtained from small molecules cannot be readily applied to prediction of the adsorption behavior of salivary macromolecules and polypeptides. The kinetics of adsorption of the salivary phosphopeptide statherin, a polyaspartate, and the salivary prolinerich phosphoprotein PRP3 are consistent with the reversibility of the adsorption process; no conclusion was possible in the case of the protein PRP1. Apparent irreversibility cannot be explained on the basis of multipoint binding or the properties of the carboxyl versus phosphate group; it appears that secondary structure determines to a significant extent the adsorption properties of the macromolecules. Calculation of the thermodynamic molar quantities of adsorption of PRP1, PRP3, andl-ASP onto HA showed that the process is entropically driven. The functional relationship between partial molar entropy and adsorption coverage is similar for the two proteins, but quite different from that for aspartate. Explanations for these results are advanced on the bases of changes in structure configurations and displacement of water from the adsorbate and the adsorbent surface, the second factor being the dominant one in the adsorption of a small molecule such asl-ASP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405293
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  • 6
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    Chemical mutation of enzyme active sites (1984)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1984-11-02
    Description: New active sites can be introduced into naturally occurring enzymes by the chemical modification of specific amino acid residues with the use of appropriately designed coenzyme analogs. The resultant semisynthetic enzymes can have catalytic activities very different from those of the corresponding native enzymes. For example, papain has been converted into a highly effective oxidoreductase by covalent modification of the sulfhydryl group of the active site cysteine residue (Cys25) with flavins such as 8-bromoacetyl-10-methylisoalloxazine. Thus, it is now possible to enhance the catalytic versatility of existing enzymes through the process of "chemical mutation" of the active site.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kaiser, E T -- Lawrence, D S -- New York, N.Y. -- Science. 1984 Nov 2;226(4674):505-11.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6238407" target="_blank"〉PubMed〈/a〉
    Keywords: Anaerobiosis ; *Binding Sites ; Catalysis ; Chemical Phenomena ; *Chemistry ; Chymotrypsin ; Enzymes/*chemical synthesis ; Flavins ; Kinetics ; NAD/metabolism ; Niacinamide/analogs & derivatives ; Oxidation-Reduction ; Papain ; Stereoisomerism ; Toluene/analogs & derivatives/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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  • 7
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    Benzodiazepine receptor synthesis and degradation by neurons in culture (1984)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1984-11-16
    Description: The benzodiazepine-gamma-aminobutyric acid receptor complex was used to study functional receptor synthesis and degradation in primary cultures of neurons. Fifty percent of the receptors turned over with an unusually rapid half-life (4 hours); this was followed by a second, slower phase (32 hours). These results provide the basis for elucidating the mechanism by which neurons derived from the central nervous system control neurotransmitter receptor number, an important problem in cellular neurobiology. The findings may be of significance in the study of neurological and psychiatric disorders.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Borden, L A -- Czajkowski, C -- Chan, C Y -- Farb, D H -- New York, N.Y. -- Science. 1984 Nov 16;226(4676):857-60.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6093257" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cells, Cultured ; Chick Embryo ; Flunitrazepam/metabolism ; Half-Life ; Kinetics ; Neurons/*metabolism ; Receptors, GABA-A/biosynthesis/*metabolism ; Spinal Cord/cytology ; gamma-Aminobutyric Acid/physiology
    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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  • 8
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    Cyclophilin: a specific cytosolic binding protein for cyclosporin A (1984)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1984-11-02
    Description: Cyclophilin, a specific cytosolic binding protein responsible for the concentration of the immunosuppressant cyclosporin A by lymphoid cells, was purified to homogeneity from bovine thymocytes. Cation-exchange high-performance liquid chromatography resolved a major and minor cyclophilin species that bind cyclosporin A with a dissociation constant of about 2 X 10(-7) moles per liter and specific activities of 77 and 67 micrograms per milligram of protein, respectively. Both cyclophilin species have an apparent molecular weight of 15,000, an isoelectric point of 9.6, and nearly identical amino acid compositions. A portion of the NH2-terminal amino acid sequence of the major species was determined. The cyclosporin A-binding activity of cyclophilin is sulfhydryl dependent, unstable at 56 degrees C and at pH 4 or 9.5, and sensitive to trypsin but not to chymotrypsin digestion. Cyclophilin specifically binds a series of cyclosporin analogs in proportion to their activity in a mixed lymphocyte reaction. Isolation of cyclophilin from the cytosol of thymocytes suggests that the immunosuppressive activity of cyclosporin A is mediated by an intracellular mechanism, not by a membrane-associated mechanism.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Handschumacher, R E -- Harding, M W -- Rice, J -- Drugge, R J -- Speicher, D W -- New York, N.Y. -- Science. 1984 Nov 2;226(4674):544-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6238408" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Carrier Proteins/*isolation & purification/metabolism ; Cattle ; Chromatography, High Pressure Liquid ; Cyclosporins/*metabolism ; Electrophoresis, Polyacrylamide Gel ; Humans ; Isoelectric Point ; Kinetics ; Lymphocyte Culture Test, Mixed ; Mice ; Molecular Weight ; Peptidylprolyl Isomerase
    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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  • 9
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    Tritiated imipramine binding sites are decreased in platelets of untreated depressed patients (1980)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1980-07-11
    Description: The high-affinity binding of triatiated imipramine to platelet membranes was compared in samples from 16 untreated depressed women and 21 age-matched controls of the same sex. The maximal binding in the depressed group was significantly lower than that of the controls, although the affinity constants were similar. These results suggest that binding of tritiated imipramine in human platelets may represent a biochemical index of depression, possibly reflecting similar changes in the brain.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Briley, M S -- Langer, S Z -- Raisman, R -- Sechter, D -- Zarifian, E -- New York, N.Y. -- Science. 1980 Jul 11;209(4453):303-5.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7384806" target="_blank"〉PubMed〈/a〉
    Keywords: Adult ; Aged ; Blood Platelets/*analysis ; Cell Membrane/metabolism ; Depression/*blood ; Humans ; Imipramine/*blood ; Kinetics ; Middle Aged ; Receptors, Drug/*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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  • 10
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    Excitatory and inhibitory effects of serotonin on sensorimotor reactivity measured with acoustic startle (1980)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1980-07-25
    Description: Serotonin infused into the lateral ventricle in rats produced a dose-dependent depression of the acoustic startle reflex. When infused onto the spinal cord, serotonin produced a dose-dependent increase in startle. Thus the same neurotransmitter can modulate the same behavior in opposite ways, depending on which part of the central nervous system is involved.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Davis, M -- Strachan, D I -- Kass, E -- New York, N.Y. -- Science. 1980 Jul 25;209(4455):521-3.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7394520" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Dose-Response Relationship, Drug ; Kinetics ; Male ; Rats ; Reflex, Acoustic/*drug effects ; Reflex, Startle/*drug effects ; Serotonin/*pharmacology
    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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