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KMID : 0545120000100020181
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Journal of Microbiology and Biotechnology
2000 Volume.10 No. 2 p.181 ~ p.186
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Inhibition of Various Proteases by MAPI and Inactivation of MAPI by Trypsin
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LEE, HYUN SOOK
KHO, YUNG HEE/LEE, KYE JOON
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Abstract
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MAPI (microbial alkaline protease inhibitor) was isolated from culture broth of Streptomyces chromofuscus SMF28. The K_i values of MAPI for the representative serine proteases such as chymotrypsin and proteinase K were 0.28 and 0.63μM, respectively, and for the cysteine proteases cathepsin B and papain were 0.66 and 0.28μM, respectively. These data indicate that MAPI is not a potent selective inhibitor of serine or cysteine proteases. Progress curves for the inhibition of three proteases by MAPI exhibited characteristic patterns: MAPI exhibited slow-binding inhibition of cathepsin B. It was rapidly associated with chymotrypsin before the addition of substrate and then reactivation of MAPI-inhibited enzyme was investigated in the presence of substrate. On the other hand, MAPI-proteinase K interaction was typical for those classical inhibitors. When MAPI was incubated with trypsin, there was an extensive reduction in the inhibitory activities of MAPI corresponding to 66.5% inactivation of MAPI, indicating that trypsin-like protease may play a role in the decrease of the inhibitory activity during cultivation.
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KEYWORD
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