Reversible inhibition of enzymes by interaction with synthetic polysaccharide macroanions

Abstract

Charged polyglucose derivatives, such as polyglucose sulfates, with different molecular weights, branching, and degree of substitution precipitated basic proteins, such as lysozyme, ribonuclease, protamine, thymus peptide, polymyxin B, an ACTH preparation, cytochrome c, and serum albumin from aqueous solution at low pH and salt concentration. Enzymic activity of lysozyme, ribonuclease (both on ribonucleic acid and on a cyclic phosphate), and hyaluronidase was inhibited in solution. The inhibition required macromolecular size and polyanionic structure and depended on the type and amount of charged groups on the synthetic polysaccharide derivative. Highly substituted sulfates were the most effective inhibitors, while sulfates with similar molecular size but lower charge density or derivatives with weaker dissociating anionic groups (carboxyls) had less inhibitory activity. The inhibition appears to be due to electrostatic interaction forces between the oppositely charged macromolecules and can be reversed by a polymeric cation stronger than the substrate.