Kininogens: inhibitors of cysteine proteinases in plasma and a similar inhibitor in chicken egg white.

Isolation, based on their inhibitory properties, is a fast and simple alternative method for the preparation of kininogens from human plasma. Pure native low Mr kininogen can be obtained in a much higher yield than with classical methods, provided that a similarly efficient inhibition of proteolysis is included. Chicken egg white also contains a high Mr inhibitor of cysteine proteinases. It closely resembles low Mr kininogen in its molecular weight, acidic isoelectric point and 1:2 inhibitor to enzyme molar binding ratio. Its relation to chicken serum kininogen is not known.