Bovine plasma HMW and LMW kininogens: isolation and characterization of the polypeptide fragments produced by plasma and tissue kallikreins.

There exist at least two types of kininogens with different molecular weight in mammalian blood plasmas, which are named high molecular weight (HMW) and low molecular weight (LMW) kininogens (1). Although their functions in kallikrein-kinin system remain to be investigated, it has been speculated that HMW kininogen participates in the intrinsic kinin releasing system and Imw kininogen in the extrinsic kinin-releasing system. Quite recently, a new function of kininogen has been suggested by findings of Flaujeac (2), Williams (3), and Fitzgerald (4) traits with a deficiency of kininogen. These plasmas do not release kinin appreciably upon incubation of plasma kallikrein and also has a prolonged activated partial thromboplastin time and inability to form plasmin. These facts suggest the participation of the kininogen in the intrinsic blood coagulation and fibrinolysis, in addition to the kinin-forming system.