Anticoagulant activity of a bacterial glycopeptide

The anticoagulant properties of myxalin, a glycopeptide secreted by a Gram negative bacterium strain (Myxococcus xanthus) are studied and compared to those of heparin. This soluble material exhibits an anticoagulant activity which implies the inhibition of some serine proteases, thrombin and factor Xa. In the presence of normal and antithrombin III-depleted plasma, myxalin inhibits the amidolytic activity of thrombin on synthetic chromogenic substrate as a function of its concentration, but fails to increase thrombin inactivation significantly in the presence of purified AT III. However, crossed immunoelectrophoresis data suggests that its antithrombi effect is mainly mediated by binding to the enzyme, rather than to AT III and probably differs from the catalytic activity of heparin which requires the presence of AT III. The anticoagulant process occurs without degradation of fibrinogen and can be neutralized by protamine.