Polymerization of protamine sulphate by carbodiimide and interaction of isolated protamine polymers with human red blood cells.

A method using a water-soluble carbodiimide to polymerize protamine sulphate is described. The behaviour of polymerized protamine in Sephadex chromatography and in polyacrylamide gel electrophoresis indicates that protamine has been polymerized into aggregates with defined molecular weights. Turbidimetrical titrations of the isolated protamine polymers with dextran sulphate show that the cationic charge density has been conserved after polymerization. The binding characteristics of the protamine polymers to human red blood cells as measured by cell electrophoresis indicate increased affinity with increased molecular weight of the polymer.