Comparative studies on the cysteine proteinase inhibitory capacity of mammalian blood

The inhibition of cysteine proteinase (papain) by human, bovine, horse, rabbit, guinea pig, rat, hamster, and mouse plasma, and pig, sheep, goat, and dog sera was investigated. The rat and mouse plasma and the pig serum showed such high inhibitory capacity as 813, 380, and 508%, respectively, of the human plasma. On the other hand, the horse, guinea pig, and rabbit plasma indicated 36, 40, and 54%, respectively, of the human plasma. A cysteine proteinase inhibitor (s) was separated from alpha-macroglobulin by Sephacryl S-300, and the inhibitory activity of all of the mammalian plasma/sera except for the guinea pig plasma appeared at around the 50-150-kDa region. The guinea pig plasma exhibited well-resolved two peaks of 100 and 200 kDa.