[Regulatory reversible enzymic reactions. Theoretical analysis].

A mathematical model has been derived and analysed describing the relationship between the rate of an enzymic reaction S1 E(R,T)A in equilibrium S2 and concentrations of substrates S1 and S2 and their analogue A capable of reversible binding to active sites of an olygomeric enzyme E(R, T). The conditions have been presented for the model to describe various types of kinetic curves, sygmoidal, curves with extremuma and intermediate plateau. The regions of parameter values have been estimated within which isosteric product activation can be observed in reactions S1 in equilibrium E(R,T) S2 and S1 E(R,T) in equilibrium S2. Two phenomena registered in experiments with olygomeric enzymes have been interpreted in the model terms, namely, the undirectional influence of isosteric and allosteric effectors on the rates of forward and reverse reactions and occurence of a reversible enzymic reaction in thermodynamically unfavourable direction. The results presented are shown to be valid for multisubstrate reactions catalysed by olygomeric enzyme E(R, T).