Complexing of trypsin with soluble copolymers based on vinyl pyrrolidone and carboxylic acids

Abstract

The authors have studied the interaction of trypsin with soluble copolymers of vinyl pyrrolidone with crotonic or methacrylic acids, containing from 4 to 30 mole % carboxylic acids. It is shown that in the neutral pH region trypsin forms with these copolymers soluble complexes of a type varying with the mode of distribution of the carboxyl groups in the polymer chain, the functional composition of the copolymers and the molar ratio of copolymer: trypsin in the initial complex system. The paper defines the optimal conditions for obtaining trypsin complexes with copolymers of vinyl pyrrolidone with crotonic acid in which trypsin completely retains enzymatic activity for protein substrates. The methods of dispersion of optical rotation and circular dichroism are used to make a detailed study of the conformational state of the trypsin macromolecules in the complexes. It is concluded that certain structural changes in trypsin lead to partial inhibition of the enzyme in the complexes obtained with a molar ratio of copolymer: trypsin < 1 in the initial complex system.