[Methods of determination of equilibrium and kinetic parameters for the interaction of protein inhibitors with proteinases].

The present-day concept of the mechanism of interaction of proteolytic enzymes with their natural protein inhibitors is discussed. An extended formal kinetic scheme of the interaction is presented. The applicability of a simplified quantitative characterization of the formation and dissociation of a stable enzyme-inhibitor complex is discussed. A critical consideration is given to the accepted approaches to determination of kinetic and equilibrium parameters of the interaction of model serine proteinases (trypsin and chymotrypsin) with common protein inhibitors of animal and plant origin. Equations are given describing the stationary rate of enzymatic hydrolysis of the respective substrate as a function of the concentrations of the reágents (substrate, inhibitor, enzyme) and kinetic and equilibrium constants. The application of some of the methods is illustrated by the interaction of trypsin and chymotrypsin with the bovine basic pancreatic inhibitor and thermo- and acid-stable inhibitor from rabbit blood serum.