Roles of polymer size and ε-amino groups in polylysine-platelet interaction

Certain aspects of poly-L-lysine (PLL) induced aggregation of human platelets have been investigated. The molecular size of PLL polymer determines their platelet aggregating activity. PLL of molecular weight (MW) 6,000 induces marked platelet aggregation at 10 −4 M, while PLL of MW 15,000 is equally active at 10 −5 M and PLL of MW 68,000 induces an equivalent degree of aggregation at 10 −6 M. Succinylation of e-amino groups of PLL results in complete loss of aggregation-inducing activity irrespective of the molecular size of the polymer. Two inhibitors of PLL-induced platelet aggregation, heparin and chondroitin sulfate, were found to react with PLL to form a PLL-inhibitor complex. Formation of this complex prevents the interaction of PLL with platelets. Succinylated PLL inhibits PLL-induced platelet aggregation in the same manner as heparin and chondroitin sulfate.