Human Factor XIII from Plasma and Platelets MOLECULAR WEIGHTS, SUBUNIT STRUCTURES, PROTEOLYTIC ACTIVATION, AND CROSS-LINKING OF FIBRINOGEN AND FIBRIN

摘要: The subunit structures of Factor XIII from plasma and platelets have been examined by sedimentation equilibrium in the ultracentrifuge. Plasma has a molecular weight 320,000 ± 20,000 dilute salt solution at neutral pH. two different types subunits factor, b chains, weights about 75,000 88,000, respectively. Platelet 146,000 10,000, whereas its single type subunit, chain, 75,000. chains platelet factors are identical not only but also on gel electrophoresis three systems amino acid composition. chain combines with factor to give protein which is electrophoretically indistinguishable native XIII. In addition, composition essentially twice average chains. These analyses indicate that structure a2b2 a2. each combined molecules solely noncovalent bonds. Thrombin, trypsin, reptilase, papain, an enzyme contaminating some ancrod preparations activate case, except possibly activation coincides decrease 4,000 chain. High concentrations thrombin slightly inactivate after prolonged incubation, trypsin activates extensively inactivates Activation autocatalyt c. Neither release fibrinopeptides nor gelation required for activated cross-link fibrinogen. γ fibrin cross-linked more rapidly than α rates cross-linking (A) fibrinogen same. pattern or guinea pig liver transglutaminase catalyzed lysis time clots was considerably greater containing little no