NONCOVALENT COMPLEXES OF ALPHA-CHYMOTRYPSIN AND A BLOCK-COPOLYMER OF ETHYLENE AND PROPYLENE OXIDES

The formation of complexes between alpha-chymotrypsin and an amphophil ic block copolymer of ethylene and propylene oxides at temperatures of 44 to 60 degrees C is demonstrated for the first time. Depending on t he temperature and the initial ratio of components, complexes of varyi ng composition and enzymatic activity are obtained. The composition of the complexes was estimated after their isolation from solution by de termination of their protein content. At higher temperatures the compl exes are enriched with polymer and have lower enzymatic activity. The complexes are very stable in water but dissociate in 8 M urea, The the rmal stability of the enzyme is enhanced in the complexes. It is propo sed that both hydrophobic interactions and hydrogen bonds between surf ace groups of protein and polymer take part in the complex formation.