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Quasi-Equilibrium Assumption in Enzyme Kinetics. Necessary and Sufficient Conditions and Accuracy of Its Application for Single-Substrate Reactions

P. V. Vrzheshch

Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 119992 Moscow, Russia; fax: (495) 939-4218; E-mail: peter@genebee.msu.ru

International Biotechnological Center, Lomonosov Moscow State University, 119992 Moscow, Russia; fax: (495) 939-5022

Received March 1, 2008; Revision received April 30, 2008
Steady-state kinetics of compulsory-ordered single-substrate irreversible and reversible enzyme reactions with two, three, and arbitrary number of intermediates were observed. Necessary and sufficient conditions for application of the quasi-equilibrium assumption and restrictions of this assumption were found in cases of two and three intermediates in the equilibrium segment. For all cases, accuracy of the quasi-equilibrium assumption was evaluated.
KEY WORDS: enzyme kinetics, quasi-equilibrium assumption, rapid equilibrium, theory, steady-state kinetics, Cha method, accuracy of assumption

DOI: 10.1134/S0006297908100076