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  • Amino Acid Sequence  (2)
  • Base Sequence
  • Chemistry
  • Inorganic Chemistry
  • 1990-1994  (3)
  • 1991  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Kinetics of the solvolysis of [Co(3Rpy)4Cl2]+ (R = Me or Et) in water + propan-2-ol mixtures (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 23 (1991), S. 161-172 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rates of solvolysis of complex ions [Co(3Rpy)4Cl2]+ with R = Me and Et have been determined in mixtures of water with the hydrophobic co-solvent propan-;2-ol for a range of temperatures. The variations of the enthalpies and entropies of activation with the solvent composition have been correlated with the physical properties of the solvent and it has been shown that the linear plot found for ΔH* against ΔS* in water + propan-2-ol is coincident with that found for water + methanol mixtures. A free energy cycle has been applied to the dissociative-type process of initial state (Cn+) going to the transition state (M(n+1)+…‥ Cl-) using values for the free energy of transfer of the chloride ion from water into the mixture, ΔGt∘(Cl-), derived from the solvent sorting technique or from the TATB/TPTB method. Irrespective of the source of ΔGt∘(Cl-), it is found that ΔGt∘(Co(3Rpy)4Cl2+*) ca. ΔGt∘(Co(3Rpy)4Cl2+) (where * indicates a species in the transition state) for mol fractions of propan-2-ol x2 ≳ 0.04-0.05 with ΔGt∘(Co(3Rpy)4Cl2+*) becoming increasingly more negative than ΔGt∘(Co(3Rpy)4Cl2+) as x2 increases above 0.05. These variations are compared with those for the solvolysis of the same ions in water + methanol mixtures and of a range of other ions in water + propan-2-ol mixtures. It is concluded that, using values for ΔGt∘(Cl-) from either source, the stabilizing influence of changes in solvent structure is greater on the cation in the transition state than on the cation in the initial state for the solvolyses of complexes [Co(Rpy)4Cl2+] and [Coen2LCl]n+.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550230207
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    Paper (German National Licenses)
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  • 2
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    Dimerization of human growth hormone by zinc (1991)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1991-08-02
    Description: Size-exclusion chromatography and sedimentation equilbrium studies demonstrated that zinc ion (Zn2+) induced the dimerization of human growth hormone (hGH). Scatchard analysis of 65Zn2+ binding to hGH showed that two Zn2+ ions associate per dimer of hGH in a cooperative fashion. Cobalt (II) can substitute for Zn2+ in the hormone dimer and gives a visible spectrum characteristic of cobalt coordinated in a tetrahedral fashion by oxygen- and nitrogen-containing ligands. Replacement of potential Zn2+ ligands (His18, His21, and Glu174) in hGH with alanine weakened both Zn2+ binding and hGH dimer formation. The Zn(2+)-hGH dimer was more stable than monomeric hGH to denaturation in guanidine-HCl. Formation of a Zn(2+)-hGH dimeric complex may be important for storage of hGH in secretory granules.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cunningham, B C -- Mulkerrin, M G -- Wells, J A -- New York, N.Y. -- Science. 1991 Aug 2;253(5019):545-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Protein Engineering, Genentech, South San Francisco, CA 94080.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1907025" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; Chromatography, Gel ; Edetic Acid/pharmacology ; Growth Hormone/*metabolism ; Humans ; Kinetics ; Macromolecular Substances ; Models, Molecular ; Protein Binding ; Protein Conformation ; Protein Denaturation ; Spectrophotometry ; Zinc/metabolism/*pharmacology
    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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  • 3
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    Dimerization of the extracellular domain of the human growth hormone receptor by a single hormone molecule (1991)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1991-11-08
    Description: Human growth hormone (hGH) forms a 1:2 complex with the extracellular domain of its receptor-binding protein (hGHbp) as studied by crystallization, size exclusion chromatography, calorimetry, and a previously undescribed fluorescence quenching assay. These and other experiments with protein engineered variants of hGH have led to the identification of the binding determinants for two distinct but adjacent sites on hGH for the hGHbp, and the data indicated that there are two overlapping binding sites on the hGHbp for hGH. Furthermore, the binding of hGH to the hGHbp occurred sequentially; a first hGHbp molecule bound to site 1 on hGH and then a second hGHbp bound to site 2. Hormone-induced receptor dimerization is proposed to be relevant to the signal transduction mechanism for the hGH receptor and other related cytokine receptors.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cunningham, B C -- Ultsch, M -- De Vos, A M -- Mulkerrin, M G -- Clauser, K R -- Wells, J A -- New York, N.Y. -- Science. 1991 Nov 8;254(5033):821-5.〈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/1948064" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Antibodies, Monoclonal ; Binding Sites ; Chromatography, Gel ; Growth Hormone/*metabolism ; Humans ; Kinetics ; Macromolecular Substances ; Models, Structural ; Molecular Sequence Data ; Mutagenesis, Site-Directed ; Protein Conformation ; Receptors, Somatotropin/genetics/isolation & purification/*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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