Human plasma kininogens are identical with α-cysteine proteinase inhibitors Evidence from immunological, enzymological and sequence data

AbstractHuman high- and low-Mr kininogens were shown to be potent inhibitors of cysteine proteinases such as cathepsin L and papain (Ki = 17–48 pM). A strong immunological cross-reaction between the kininogens and low-Mr α-cysteine proteinase inhibitor from human plasma was found. Comparison of partial amino acid sequences from high- and low-Mr kininogen and low-Mr α-cysteine proteinase inhibitor demonstrated sequence identity for all segments analyzed. These findings suggest that the kininogens and the α-cysteine proteinase inhibitors from human plasma are identical proteins