[Thermodynamics changes in catalytic properties of immobilized enzymes]

Study of the temperature dependence of hydrolysis of the ethyl ester N-acetyl-L-tyrosine and p-nitroanilide N-succinyl-L-phenylalanine by chymotrypsin and polymaleic acid-modified chymotrypsin showed that the enthalpy and enthropy of dissociation of the enzyme-substrate complex and those of activation of the enzyme acylation in the course of catalysis increase during the native enzyme transition to its modified form. The data obtained can be explained terms of changes in the native conformation of the enzyme during its modification, which is confirmed by the previously obtained data on thermodenaturation. Some part of the energy of substrate binding is consumed for changing the conformation of the modified protein, rendering it close to the native one and thus providing a further enzymatic catalysis which is similar to that by the native enzyme.