Standard Gibbs Free Energy, Enthalpy, and Entropy Changes as a Function of pH and pMg for Several Reactions Involving Adenosine Phosphates

Journal of Biological Chemistry (Impact Factor: 4.57). 07/1969; 244(12):3290-302.
Source: PubMed
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    • "Over a Christmas holiday in the Krebs laboratory in 1967, I determined the equilibrium constant of the combined glyceraldehyde-3-phosphate dehydrogenase plus 3-phosphoglycerate kinase reactions, which in the absence of free Mg 2ϩ I found to be 59. At the time, I was unaware of the effects that variations of free [Mg 2ϩ ] would have in reactions in which the Mg binding constants of the substrates and products differed significantly, a fact that was clearly explained by Robert Alberty [26] soon after these results were obtained. My value was incorrect "
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    ABSTRACT: This paper reviews the development in the 1950s of methods to determine the redox states of the free [NAD(+) ]/[NADH] in cytoplasm of yeast by Helmut Holzer and Feodore Lynen and in rat liver by Theodore Bucher and Martin Klingenberg. This work was extended in the 1960s in the laboratory of Hans Krebs, where the use of basic thermodynamic and kinetic principles allowed the extension of this approach to the determination of the free mitochondrial [NAD(+) ]/NADH] in mitochondria and the redox state of the free NADP system in cytoplasm and mitochondria. This work also outlined the linkage between the redox states in the various couples to the phosphorylation state or the free [ATP]/[ADP][P(i) ] ratio, the central energy parameter of living cells. This work has since been extended to include other energy-linked systems including the gradients of inorganic ions between extra and intracellular phases of the cell and the redox state of the co-enzyme Q couple of mitochondria. This system of linked near-equilibrium redox and phosphorylation potentials constitutes a framework of primitive metabolic control that is altered in a number of disease phenotypes. The alteration of such disease phenotypes by substrate availability is discussed, as well as the importance of a thorough grounding in basic kinetics and thermodynamics in designing new therapies to normalize the metabolic abnormalities that are the proximate cause of many common and some rare diseases states.
    Biochemistry and Molecular Biology Education 05/2006; 34(3):168-79. DOI:10.1002/bmb.2006.49403403168 · 0.59 Impact Factor
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    • "The fitting program was TableCurve (Jandel). The number of Mg2+ ions participating in the interaction was estimated as described (Alberty, 1969). "
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    ABSTRACT: Elongation factor Tu (EF-Tu) from Escherichia coli carrying the mutation G222D is unable to hydrolyze GTP on the ribosome and to sustain polypeptide synthesis at near physiological Mg2+ concentration, although the interactions with guanine nucleotides and aminoacyl-tRNA are not changed significantly. GTPase and polypeptide synthesis activities are restored by increasing the Mg2+ concentration. Here we report a pre-steady-state kinetic study of the binding of the ternary complexes of wild-type and mutant EF-Tu with Phe-tRNA(Phe) and GTP to the A site of poly(U)-programed ribosomes. The kinetic parameters of initial binding to the ribosome and subsequent codon-anticodon interaction are similar for mutant and wild-type EF-Tu, independent of the Mg2+ concentration, suggesting that the initial interaction with the ribosome is not affected by the mutation. Codon recognition following initial binding is also not affected by the mutation. The main effect of the G222D mutation is the inhibition, at low Mg2+ concentration, of codon-induced structural transitions of the tRNA and, in particular, their transmission to EF-Tu that precedes GTP hydrolysis and the subsequent steps of A-site binding. Increasing the Mg2+ concentration to 10 mM restores the complete reaction sequence of A-site binding at close to wild-type rates. The inhibition of the structural transitions is probably due to the interference of the negative charge introduced by the mutation with negative charges either of the 3' terminus of the tRNA, bound in the vicinity of the mutated amino acid in domain 2 of EF-Tu, or of the ribosome. Increasing the Mg2+ concentration appears to overcome the inhibition by screening the negative charges.
    The EMBO Journal 01/1997; 15(23):6766-74. · 10.75 Impact Factor
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    ABSTRACT: Vita. Thesis (Ph. D.)--University of British Columbia, 1986. Includes bibliographical references (leaves 140-153).
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