Novel polypeptides (NPs) are provided which are capable of protein C activation without significant fibrinogen clotting activity, and vice versa. NPs having enhanced protein C activating properties in relation to fibrinogen clotting are useful in particular as anticoagulants and in screening for substances that agonize or antagonize this property and in diagnostic procedures to determine the status of patients' activated protein C-mediated anticoagulant pathway. Procoagulant NPs are useful to promote clotting in the course of therapy of solid tumors, as an impregnate for bandages, or in diagnostic assays. The NPs are produced in recombinant cell culture or by in vitro methods.