Properties of cysteine proteinase inhibitors from black gram and rice bean

Cysteine proteinase inhibitors (CPI) were purified to 59 and 54 fold from b lack gram (Vigna mungo (L.) Hepper) and rice bean (Vigna umbellata Thunb.), respectively, by using heat treatment, followed by chromatography on a car boxymethyl (CM)-papain-Sepharose affinity column. The purified inhibitors w ere highly inhibitory to papain and Pacific whiting cathepsin L in a concen tration dependent manner. They were detected as a dark band on tricine-SDS- PACE gel stained for inhibitory activity. The apparent molecular weights of purified CPI from black gram and rice bean seeds were estimated to be 12,0 00 daltons. The purified inhibitors were thermostable up to 90C and active in the neutral and alkaline pH ranges.