A Bowman-Birk-type trypsin-chymotrypsin inhibitor from broad beans

An isolation procedure comprising affinity chromatography on Affi-gel blue gel, ion exchange chromatography on SP-Toyopearl, and fast protein liquid chromatography on Mono S was used to purify a peptide from broad beans which manifested antifungal activity toward Mycosphaerella arachidicola, Fusarium oxysporum, and Botrytis cinerea. The peptide demonstrated a molecular mass of 7.5 kDa. N-terminal sequence analysis disclosed the identity of the antifungal peptide to be a trypsin-chymotrypsin inhibitor. The trypsin-chymotrypsin inhibitor also exerted an inhibitory action on chymotrypsin activity and HIV-1 reverse transcriptase activity. Proliferation of murine splenocytes was stimulated in the presence of the trypsin-chymotrypsin inhibitor. This report constitutes the first observation of antifungal activity of a leguminous peptidic protease inhibitor. (C) 2001 Academic Press.