[Evaluation of kinetic parameters of unpurified enzymic systems, method for measuring the concentration of endogenous...

A universal method is proposed for determining concentration of the endogenous substrate S (notwithstanding its concrete nature) in unpurified enzymic systems, whose behaviour is described by the equation of Michaelis - Menten type. The approach is based on measurement and analysis of the values of apparent Michaelis constant, characterizing the formation kinetics of labelled product from the labelled substrate S added to the system. The method for calculating S is at the same time valid for calculating real values of v, V and Km for the samples of unpurified enzymes, which contain unknown amounts of endogenous substrate.