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  • 1
    Publication Date: 1992-06-26
    Description: A 3.5 angstrom resolution electron density map of the HIV-1 reverse transcriptase heterodimer complexed with nevirapine, a drug with potential for treatment of AIDS, reveals an asymmetric dimer. The polymerase (pol) domain of the 66-kilodalton subunit has a large cleft analogous to that of the Klenow fragment of Escherichia coli DNA polymerase I. However, the 51-kilodalton subunit of identical sequence has no such cleft because the four subdomains of the pol domain occupy completely different relative positions. Two of the four pol subdomains appear to be structurally related to subdomains of the Klenow fragment, including one containing the catalytic site. The subdomain that appears likely to bind the template strand at the pol active site has a different structure in the two polymerases. Duplex A-form RNA-DNA hybrid can be model-built into the cleft that runs between the ribonuclease H and pol active sites. Nevirapine is almost completely buried in a pocket near but not overlapping with the pol active site. Residues whose mutation results in drug resistance have been approximately located.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kohlstaedt, L A -- Wang, J -- Friedman, J M -- Rice, P A -- Steitz, T A -- GM 39546/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1992 Jun 26;256(5065):1783-90.〈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/1377403" target="_blank"〉PubMed〈/a〉
    Keywords: Azepines/pharmacology ; Binding Sites ; Crystallography ; DNA Polymerase I/chemistry ; Escherichia coli/genetics ; HIV-1/*enzymology ; Models, Molecular ; Molecular Structure ; Nevirapine ; Protein Conformation ; Pyridines/pharmacology ; RNA-Directed DNA Polymerase/*chemistry
    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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  • 2
    Publication Date: 1988-04-08
    Description: Site-directed mutagenesis of the large fragment of DNA polymerase I (Klenow fragment) yielded two mutant proteins lacking 3',5'-exonuclease activity but having normal polymerase activity. Crystallographic analysis of the mutant proteins showed that neither had any alteration in protein structure other than the expected changes at the mutation sites. These results confirmed the presumed location of the exonuclease active site on the small domain of Klenow fragment and its physical separation from the polymerase active site. An anomalous scattering difference Fourier of a complex of the wild-type enzyme with divalent manganese ion and deoxythymidine monophosphate showed that the exonuclease active site has binding sites for two divalent metal ions. The properties of the mutant proteins suggest that one metal ion plays a role in substrate binding while the other is involved in catalysis of the exonuclease reaction.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Derbyshire, V -- Freemont, P S -- Sanderson, M R -- Beese, L -- Friedman, J M -- Joyce, C M -- Steitz, T A -- GM-22778/GM/NIGMS NIH HHS/ -- GM-28550/GM/NIGMS NIH HHS/ -- RR-01644/RR/NCRR NIH HHS/ -- New York, N.Y. -- Science. 1988 Apr 8;240(4849):199-201.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biophysics and Biochemistry, Yale University Medical School, New Haven, CT 06510.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2832946" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Catalysis ; Computer Graphics ; Crystallography ; DNA Mutational Analysis ; *DNA Polymerase I/genetics ; Escherichia coli/enzymology ; Exonucleases ; Metals ; Models, Molecular ; Protein Conformation ; Structure-Activity Relationship
    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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  • 3
    Publication Date: 1987-10-16
    Description: Inhomogeneous broadening of the 760-nanometer photoproduct band of carboxymyoglobin at cryogenic temperatures has been demonstrated with a dynamic hole burning technique. Line-shape changes and frequency shifts in this spectral band are generated by ligand recombination and are shown not to be the result of structural relaxation below 60 K. The observation of dynamic hole burning exposes the relation between the structural disorder responsible for the inhomogeneous broadening and the well-known distributed ligand rebinding kinetics. The findings provide direct evidence for the functional relevance of conformational substrates in myoglobin rebinding. In addition, a general protocol for evaluating the relative contributions of structural relaxation and hole burning to the spectral changes accompanying rebinding in hemeproteins is presented.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Campbell, B F -- Chance, M R -- Friedman, J M -- HL-18708/HL/NHLBI NIH HHS/ -- P30 EB009998/EB/NIBIB NIH HHS/ -- New York, N.Y. -- Science. 1987 Oct 16;238(4825):373-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉AT&T Bell Laboratories, Murray Hill, NJ 07974.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3659921" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Carbon Monoxide/metabolism ; Kinetics ; Myoglobin/*metabolism ; Photochemistry ; Protein Binding ; Protein Conformation ; Spectrophotometry ; Spectrophotometry, Infrared ; Temperature
    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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  • 4
    Publication Date: 1985-08-16
    Description: Picosecond time-resolved Raman spectra of hemoglobin generated with blue pulses (20 to 30 picoseconds) that were resonant with the Soret band and of sufficient intensity to completely photodissociate the starting liganded sample are reported. For both R- and T-state liganded hemoglobins, the peak frequencies in the spectrum of the deoxy transient were the same at approximately 25 picoseconds as those observed at 10 nanoseconds subsequent to photodissociation. In particular, the large R-T differences in the frequency of the stretching mode for the iron-proximal histidine bond (VFe-His) detected in previously reported nanosecond-resolved spectra were also evident in the picosecond-resolved spectra. The implications of this finding with respect to the distribution of strain energy in the liganded protein and the origin of the time course for geminate recombination are discussed. On the basis of these results, a microscopic model is proposed in which delocalization of strain energy is strongly coupled to the coordinate of the iron. The model is used to explain the origin of the R-T differences in the rates of ligand dissociation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Findsen, E W -- Friedman, J M -- Ondrias, M R -- Simon, S R -- 2-506 RR-8139/RR/NCRR NIH HHS/ -- R01 GM3333O-01/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1985 Aug 16;229(4714):661-5.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/4023704" target="_blank"〉PubMed〈/a〉
    Keywords: Allosteric Regulation ; *Hemoglobin A ; Humans ; Motion ; Protein Conformation ; Spectrum Analysis, Raman ; Structure-Activity Relationship ; Thermodynamics
    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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  • 5
    Publication Date: 1985-07-12
    Description: The picosecond geminate rebinding of molecular oxygen was monitored in a variety of different human, reptilian, and fish hemoglobins. The fast (100 to 200 picoseconds) component of the rebinding is highly sensitive to protein structure. Both proximal and distal perturbations of the heme affect this rebinding process. The rebinding yield for the fast process correlates with the frequency of the stretching motion of the iron-proximal histidine mode (VFe-His) observed in the transient Raman spectra of photodissociated ligated hemoglobins. The high-affinity R-state species exhibit the highest values for VFe-His and the highest yields for fast rebinding, whereas low affinity R-state species and T-state species exhibit lower values of VFe-His and correspondingly reduced yields for this geminate process. These findings link protein control of ligand binding with events at the heme.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Friedman, J M -- Scott, T W -- Fisanick, G J -- Simon, S R -- Findsen, E W -- Ondrias, M R -- Macdonald, V W -- 1 R01 GM 33330-1/GM/NIGMS NIH HHS/ -- DHHS2-S06/DH/BHP HRSA HHS/ -- RR08139/RR/NCRR NIH HHS/ -- New York, N.Y. -- Science. 1985 Jul 12;229(4709):187-90.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/4012316" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Fishes ; Heme/metabolism ; Hemoglobins, Abnormal/*genetics/metabolism ; Humans ; Ligands/metabolism ; Oxygen/metabolism ; Protein Binding ; Protein Conformation
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    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 6
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1985-06-14
    Description: The static structure of hemoglobin and its functional properties are very well characterized. It is still not known how energy is stored and used within the structure of the protein to promote function and functional diversity. An essential part of this question is understanding the mechanism through which the overall protein structure (quaternary structure) couples to the local environment about the oxygen binding sites. Time-resolved resonance Raman spectroscopy has been used to probe the vibrational degrees of the freedom of the binding site as a function of protein structure. Comparison of the spectra from both equilibrium and transient forms of deoxy hemoglobin from a variety of mammalian, reptilian, and fish hemoglobins reveals that for each quaternary structure there exist two tertiary states stabilized by the presence or absence of an iron-bound ligand. Pulse-probe Raman experiments show that for photodissociated, ligated hemoglobins the local tertiary structure relaxes at a solution-dependent rate extending from tens of nanoseconds to microseconds. In this local environment, the linkage between the iron and the proximal histidine proves to be the single observed structural feature that responds in a systematic and substantial manner to structural changes in the protein. The additional finding of a correlation between the frequency of the iron-proximal histidine stretching motion (nu Fe-His) and various parameters of ligand reactivity, including geminate recombination, implicates the associated localized structural element in the mechanism of protein control of ligand binding. On the basis of these and related finds, a model is presented to account for both coarse and fine control of ligand binding by the protein structure.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Friedman, J M -- New York, N.Y. -- Science. 1985 Jun 14;228(4705):1273-80.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/4001941" target="_blank"〉PubMed〈/a〉
    Keywords: Allosteric Regulation ; Animals ; Carboxyhemoglobin ; Cold Temperature ; *Hemoglobins ; Histidine ; Humans ; Hydrogen-Ion Concentration ; Iron ; *Oxyhemoglobins ; Protein Conformation ; Spectrum Analysis, Raman ; Structure-Activity Relationship ; Thermodynamics
    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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