Effect of microbial and mite proteases on low and high molecular weight kininogens. Generation of kinin and inactivation of thiol protease inhibitory activity.

Kinin release from guinea pig plasma high molecular weight kininogen (HMWK) induced by various microbial and mite proteases has been demonstrated previously (Molla, A., Yamamoto, T., Akaike, T., Miyoshi, S., and Maeda, H. (1989) J. Biol. Chem. 264, 10589-10594; Maruo, K., Akaike, T., Matsumura, Y., Kohmoto, S., Inada, Y., Ono, T., Arao, T., and Maeda, H. (1991) Biochim. Biophys. Acta 1074, 62-68). In this paper, we describe the effects of various microbial and mite proteases on low molecular weight kininogen (LMWK) and HMWK from human plasma. A protease from the house dust mite Dermatophagoides farinae (Df-protease) directly liberated kinin from both LMWK and HMWK to a significant degree. The Km, kcat, and kcat/Km values for kinin generation from LMWK were 3.24 microM, 0.61 s-1, and 1.9 x 10(5) M-1 x s-1, respectively, and those for kinin generation from HMWK were 0.56 microM, 0.12 s-1, and 2.1 x 10(5) M-1 x s-1, respectively; kcat/Km values for Df-protease were comparable with that for glandular kallikrein. In contrast, microbial proteases showed only weak kinin-releasing activity from both human plasma kininogens. Four of ten different microbial proteases liberated kinin from LMWK, and only serratial 56-kDa protease released kinin from HMWK. Furthermore, Df-protease markedly inactivated the thiol protease inhibitory activity of LMWK and HMWK, whereas all microbial proteases (as well as the endogenous protease trypsin) did not affect this inhibitory activity of both kininogens from human plasma.