pH Variation of isotope effects in enzyme-catalyzed reactions. 2. Isotope-dependent step not pH dependent. Kinetic mechanism of alcohol dehydrogenase

Biochemistry ◽  
1981 ◽  
Vol 20 (7) ◽  
pp. 1805-1816 ◽  
Author(s):  
Paul F. Cook ◽  
W. W. Cleland
Keyword(s):  
Alcohol Dehydrogenase ◽  
Isotope Effects ◽  
Kinetic Mechanism ◽  
Ph Variation ◽  
Ph Dependent ◽  
Catalyzed Reactions ◽  
Enzyme Catalyzed Reactions

pH Variation of isotope effects in enzyme-catalyzed reactions. 1. Isotope- and pH-dependent steps the same

Biochemistry ◽  
1981 ◽  
Vol 20 (7) ◽  
pp. 1797-1805 ◽  
Author(s):  
Paul F. Cook ◽  
W. W. Cleland
Keyword(s):  
Isotope Effects ◽  
Ph Variation ◽  
Ph Dependent ◽  
Catalyzed Reactions ◽  
Enzyme Catalyzed Reactions

Steady-State Enzyme Kinetics at High Pressure

1996 ◽  
Author(s):  
Dexter B. Northrop
Keyword(s):  
Transition State ◽  
Conformational Changes ◽  
Isotope Effects ◽  
Enzymatic Reaction ◽  
Kinetic Mechanism ◽  
Point Of View ◽  
Pressure Effects ◽  
Volume Changes ◽  
Catalyzed Reactions ◽  
Enzyme Catalyzed Reactions

Pressure effects on enzyme-catalyzed reactions were traditionally interpreted within a simplistic kinetic mechanism in which the transition state presented the highest energy barrier, and the chemical transformation of substrate to product was considered to be a singular, rate-limiting step. This was also true of isotope effects on enzyme-catalyzed reactions, but extensive isotopic studies have led to the conclusion that this transition state is rarely the highest barrier. Rather, the release of products (or the conformational change preceding product release) is usually the slowest step, often accompanied by several other partially ratelimiting steps. Thus, our interpretations of pressure effects must be shifted accordingly. Values attributed to AV‡ have been determined for more than 50 enzymes, more of them with a positive sign than negative, and most in the range of 20 to 40 ml mol–1 but these may or may not have anything to do with the activation volume associated with the transition state. Volume changes specifically associated with the binding of ligands to enzymes have been reported as well, including some very large values, as high as ΔV = 85 ml mo–1. Kinetically, these equilibrium pressure effects also originate in conformational changes because water is not very compressible; hence, rates of diffusion to and from enzymes are virtually unaffected by pressure. Much larger changes, as high as ΔV = –391 mi mo–1, have been observed during disaggregation and denaturation of enzymes. Thus, while it is possible for pressure effects to be expressed on every step of an enzymatic reaction, and to cause denaturation as well, making kinetic data from pressure effects hopelessly complex and uninterpretable, it appears likely that the most significant pressure effects will be expressed on conformational changes associated with product dissociations, without much kinetic complexity. This makes sense from another point of view—that the largest volume changes are probably on solvation equilibria during ligand binding and protein folding. Pressure effects on isotope effects have the potential of specifically identifying whether or not a volume change occurs upon attaining the transition state. With the exception of hydrogen tunneling, intrinsic isotope effects are independent of pressure.

Secondary deuterium and nitrogen-15 isotope effects in enzyme-catalyzed reactions. Chemical mechanism of liver alcohol dehydrogenase

Biochemistry ◽  
1981 ◽  
Vol 20 (7) ◽  
pp. 1817-1825 ◽  
Author(s):  
Paul F. Cook ◽  
Norman J. Oppenheimer ◽  
W. W. Cleland
Keyword(s):  
Alcohol Dehydrogenase ◽  
Isotope Effects ◽  
Chemical Mechanism ◽  
Liver Alcohol Dehydrogenase ◽  
Catalyzed Reactions ◽  
Enzyme Catalyzed Reactions

scholarly journals Isomerization of an enzyme-coenzyme complex in yeast alcohol dehydrogenase-catalysed reactions

2003 ◽  
Vol 68 (2) ◽  
pp. 77-84 ◽  
Author(s):  
Vladimir Leskovac ◽  
Svetlana Trivic ◽  
Draginja Pericin
Keyword(s):  
Alcohol Dehydrogenase ◽  
Rate Constants ◽  
Equilibrium Constants ◽  
Kinetic Mechanism ◽  
Yeast Alcohol Dehydrogenase ◽  
Catalyzed Reactions ◽  
The Individual ◽  
Individual Rate ◽  
Catalyzed Oxidation

In this work, all the rate constants in the kinetic mechanism of the yeast alcohol dehydrogenase-catalyzed oxidation of ethanol by NAD+, at pH 7.0, 25 ?C, have been estimated. The determination of the individual rate constants was achieved by fitting the reaction progress curves to the experimental data, using the procedures of the FITSIM and KINSIM software package of Carl Frieden. This work is the first report in the literature showing the internal equilibrium constants for the isomerization of the enzyme-NAD+ complex in yeast alcohol dehydrogenase-catalyzed reactions.

scholarly journals Multiple Isotope Effects on Enzyme-Catalyzed Reactions

1989 ◽  
Vol 58 (1) ◽  
pp. 377-401 ◽  
Author(s):  
M H O'Leary
Keyword(s):  
Isotope Effects ◽  
Catalyzed Reactions ◽  
Enzyme Catalyzed Reactions

Isotope effects on enzyme-catalyzed reactions

1992 ◽  
Vol 2 (10) ◽  
pp. 548
Author(s):  
Vernon E. Anderson
Keyword(s):  
Isotope Effects ◽  
Catalyzed Reactions ◽  
Enzyme Catalyzed Reactions

Calculations of intrinsic isotope effects and the detection of tunneling in enzyme-catalyzed reactions

1990 ◽  
Vol 18 (4) ◽  
pp. 435-439 ◽  
Author(s):  
Dexter B. Northrop ◽  
Ronald G. Duggleby
Keyword(s):  
Isotope Effects ◽  
Catalyzed Reactions ◽  
Enzyme Catalyzed Reactions

Primary and secondary deuterium isotope effects on equilibrium constants for enzyme-catalyzed reactions

Biochemistry ◽  
1980 ◽  
Vol 19 (21) ◽  
pp. 4853-4858 ◽  
Author(s):  
Paul F. Cook ◽  
John S. Blanchard ◽  
W. W. Cleland
Keyword(s):  
Isotope Effects ◽  
Equilibrium Constants ◽  
Deuterium Isotope Effects ◽  
Catalyzed Reactions ◽  
Enzyme Catalyzed Reactions
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