Enzymatic degradation of heparin-related mucopolysaccharides from the surface of endothelial cell cultures

Abstract

When cultures of endothelial cells prelabeled with H2 -35-SO4 are exposed to a purified preparation from induced Flavobacterium heparinum containing heparinase and heparitinase activities, radioactivity accumulates in the supernatant medium. After further treatment in vitro with crude enzyme this material migrates, in part, as glucosamine (N,O-disulfated glucosamine), a break-down product characteristic of heparin and heparin-related mucopolysaccharides. After exposure of the cultures to the purified enzyme, the amount of acid-insoluble -3 5-S radioactivity that can be removed with EDTA is decreased compared to that that can be removed from control cultures. Since the amount of radioactivity that is released as break-down products is much higher than the amount of radioactivity that is secreted into the supernatant medium as intact (non-dialysable) mucopolysaccharide chains in control plates, the action of the enzyme appears to be on the cell itself. The data presented support previous studies suggesting that chains of heparitin sulfate that are accessible to the action of the enzyme are present at the surface of endothelial cells.