1988 Fiscal Year Final Research Report Summary

The possibility of the double head of leguminous STI(Kunitz) family inhibitors.

Research Project

Project/Area Number	62580121
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	物質生物化学
Research Institution	Osaka University
Principal Investigator	HARA Saburo Faculty of Science, Osaka University, Associate Professor, 理学部, 助教授 (00028193)
Project Period (FY)	1987 – 1988
Keywords	Soybean trypsin inhibitor (Kunitz) / winged bean chymotrypsin inhibitor / Inhibition mechanism / 第二阻害反応部位
Research Abstract	1) The complete amino acid sequence of winged bean chymotrypsin inhibitor 3 (WCI-3) was determined by the conventional methods. WCI-3 consisted of 183 amino acid residues, but was heterogeneous in the carboxyl terminal region. The sequence of WCI-3 was highly homologous with those of STI(Kunitz) family inhibitors. 2) WCI-3 was treated with porcine chymotrypsin at pH 3.0. Chymotrypsin, however, hydrolyzed only the first reactive site (Leu(65)-Ser(66)). Onthe trial to cleave the second reactive site oF WCI-3 using several chymotrypsin-family enzymes, elastase, subtilisin, SGPS and SGPB, no enzyme could cleave the peptide bond of the second reactive site. The similar studies were done using the soybean trypsin inhibitor (Kunitz) (STI) Ti^a. The results suggested that the second reactive site of Ti^a might be located at or near Met(84)-Leu(85).