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L. N. Christophorov
«Notes to the Centenary of Michaelis–Menten’s Scheme»
541–550 (2020)

PACS numbers: 05.65.+b, 82.37.Np, 82.39.Fk, 82.65.+r, 87.14.ej, 87.15.A-, 87.15.R-

The Michaelis–Menten’s (MM) scheme serves as a basis for enzymatic kinetics rather long since. Early attempts to search for internal mechanisms of regulation of enzyme activity rooted in the conformational lability and for corresponding deviations from the classical kinetics were practically ignored for a prolonged period. Nowadays, however, there is no lack of theoretical papers devoted to various MM-like schemes. This is mainly conditioned by implementation of the single-molecule (SM) methods into enzymology, and by similarities to heterogeneous (nano)catalysis with its direct analogue to the MM scheme called Langmuir–Hinshelwood’s model. It is expedient to assess the interim achievements on this way. With this purpose, the most basic example, namely, reactions of monomeric enzymes with an only binding site, is considered. In this generic case, it is especially clear, which new possibilities arise due to conformational fluctuations of the enzyme and how transparent is their physical nature. The minimal MM-like schemes, which exhaust all the characteristic regulation phenomena caused by the presence of conformational channels (non-monotonic dependence of the velocity on the rate of substrate release, cooperativity, and substrate inhibition), are described. An alternative approach based on our previously proposed concept of molecular self-organization to the enzyme functioning along the lines of nonequilibrium phase transitions is outlined.

Keywords: enzymatic reactions, Michaelis–Menten’s schemes, monomeric enzymes, conformational regulation, reaction velocity