Purification and properties of human low molecular weight kininogen.

A three-step isolation procedure has been developed for human low molecular weight kininogen resulting in a 385-fold purification of the protein from plasma with an accumulative yield of 8.4%. Human low molecular weight kininogen is a single-chain glycoprotein of apparent molecular weight of 68,000 with a blocked amino-terminus. In the absence of dissociating agents, low molecular weight kininogen reversibly forms homo-oligomers with apparent Mr 185,000 (dimer) to 780,000 (decamer). Limited proteolysis of low molecular weight kininogen by tissue kallikrein liberates kinin and results in the formation of a two-chain molecular with an Mr 62,000 heavy chain of apparent Mr 4000.