Partial purification and characterization of bapa-ase fromVigna unguiculata (L.) walp

α-N-Benzoyl-DL-arginine-p-nitroanilide (BAPA) hydrolytic enzyme was partially purified from cotyledons of mature dry seeds ofVigna unguiculata (L.) Walp, cv. Seridó. Extracts of a finely ground meal ofVigna seeds were obtained with 0.02 M phosphate buffer (KH₂PO₄/ /Na₂HPO₄) pH 7.6. A protein fraction was obtained from the extracts by ammonium sulfate precipitation (25 to 50% saturation). This protein fraction was subjected to chromatography on DEAE-cellulose. A separated fraction of the cellulose column presented one main component and two minor bands as seen on polyacrylamide gels. The main component of the separated fraction gave a positive reaction with BAPA and acetyl-DL-phenylalanine-β-naphthyl ester (APNE). This fraction shows a molecular mass of 60 000 by gel filtration on Sephadex G-100, pH 7.6. The BAPA-ase activity was stable at pH values of 7.0 to 9.0 and no decrease in activity was observed by heating at 40 °C up to 40 min. The activity was not affected by PMSF, EDTA, cysteine,p- CMB, and IAC but was inhibited by NEM and strongly inhibited by TLCK. Leucine-p-nitroanilide (LPA) hydrolytic enzyme properties were also determined. This activity was inhibited by PMSF,p- CMB, and NEM.