[Effect of electrostatic interactions on formation and properties of soluble heteroprotein conjugates based on...

The regularities of directed polycondensation of proteins with opposite charges by glutaric aldehyde were studied using serum albumin and proteolytic enzymes (urokinase, trypsin, alpha-chymotrypsin) as models. The electrostatic interaction of oppositely charged protein macromonomers in the polycondensation process was shown to facilitate the selective synthesis of soluble heteroprotein conjugates with molecular mass from 2 x 10(5) to 9 x 10(5); these conjugates have controlled component composition, high enzyme content (up to 3 to 4 molecules of an enzyme per one albumin molecule) and completely retain the enzyme catalytic activity. The dependence of rate constants and activation parameters of thermal inactivation of the heteroconjugates upon their composition, molecular mass and the degree of modification of the protein amino groups was investigated. Heteroconjugates of electrically asymmetric proteins, in particular, trypsin and serum albumin, were found to be several hundred times more stable than the starting enzymes at 38-60 degrees C.