Bullfrog plasma cysteine proteinase inhibitor (CPI).
Papain is inhibited by bullfrog plasma. CPI was isolated from bullfrog plasma by two step column chromatography; Cm-papain agarose column chromatography followed by FPLC Mono Q column chromatography with addition of benzamidine. Isolated CPI gave a single band on SDS-PAGE under reducing condition, and the molecular weight of reduced CPI was estimated to be over 200 kDa. When the isolated CPI was stored at 4 degrees C in the absence of benzamidine, the CPI was cleaved and yielded a protein consisting of heavy chain (60 kDa) and light chain (54 kDa). Both chains were linked with disulfide bond(s). The cleaved form of CPI was also isolated from the plasma in the absence of benzamidine. Intact and cleaved form of CPI inhibited papain and ficin, but not trypsin.
Mashiko
H
H
Division of Chemistry of Hygiene, Meiji College of Pharmacy, Tokyo, Japan.
Takahashi
H
H
D000818:Animals; D015853:Cysteine Proteinase Inhibitors / Q000097:blood*; D011892:Rana catesbeiana / Q000378:metabolism*
D015853:Cysteine Proteinase Inhibitors