Competitive inhibition of myosin ATPase activity by different molecular weight heparins

Myosin ATPase activity was measured, by continuous luminometric method, in presence of different molecular weight heparins. ATPase activity decreases in the presence of heparin, when simultaneous incubation with ATP is carried out; the percentage of inhibition is proportional to polysaccharide concentration. Heparins of different molecular weights (1.75 KD to 11.6 KD) are competitive inhibitors of enzymatic activity; the inhibitory effects is also appreciable with trisulphated disaccharide. The possible mechanisms of interaction between heparin and myosin ATPase are discussed.