SUBSTRATE SPECIFICITY OF AMINOPEPTIDASE FROM JAPANESE CLASSIFIED BARLEY FLOUR

In this study, some properties of a peptidase obtained from Japanese barley were investigated. Boc‐Val‐Leu‐Lys‐MCA was slightly hydrolyzed, but the enzyme showed almost no activity on Suc‐Ala‐Ala‐Pro‐Phe‐MCA and Ac‐Val‐Glu‐Ile‐Asp‐MCA. The enzyme activity decreased to 57.7% by the addition of 0.235 mM bestatin. All tripeptides and tetrapeptides studied were cleaved from the N‐terminus amino acid by the enzyme. However, the enzyme did not cleave Leu‐Pro‐Phe‐Phe‐Asp in the manner of the AP type. The C‐terminus amino acid residue (Asp) and the second amino acid residue of the C‐terminus (Phe) were released at almost the same time. From these findings, this enzyme was identified as both an AP and oligopeptidase. This property is very similar to that of cathepsin H and the novel peptidase purified from mesquite pollen. This enzyme may not only supply useful foodstuffs such as a meat tenderizer but also produce bioactive peptides.