BIOCHEMICAL AND CHROMATOGRAPHIC STUDIES OF CERTAIN ACTIVITIES ASSOCIATED WITH HUMAN FIBRINOGEN PREPARATIONS*

Abstract

Studies were made of biological activities associated with the types of human fibrinogen distinguishable by their chromatographic behavior on DEAE cellulose. No significant differences in thrombin clotting times were detected. A previously unsuspected inhibitor of plasmin and trypsin, present in all unchromatographed preparations examined, was revealed by comparison of the sensitivities of various chromatographic fractions of fibrinogen to digestion by plasmin and trypsin. Kinetic data indicated that with respect to plasmin acting on a fibrin substrate the inhibitor was competitive. The ascending portion of the first major chromatographic peak was free of inhibitor activity within the range of substrate concentrations studied. The inhibitor was not identical with fibrin stabilizing factor activity. Chromatography was an efficient method for preparing fibrin stabilizing factor free fibrinogen.