Purified yeast aspartic protease 3 cleaves anglerfish pro‐somatostatin I and II at di‐ and monobasic sites to generate somatostatin‐14 and ‐28

Abstract

Anglerfish somatostatin‐14 (SS‐14) and somatostatin‐28 (aSS‐28) are derived from pro‐somatostatin I (aPSS‐I) and pro‐somatostatin II (PSS‐II), respectively. Purified yeast aspartic protease 3 (YAP3), was shown to cleave aPSS‐I at the Arg¹⁸‐Lys⁸² to yield SS‐14 and Lys⁻¹SS‐H. In contrast, YAP3 cleaved aPSS‐II only at the monobasic residue. Arg⁷³ to yield aSS‐28. Since the paired basic and monobasic sites are present in both precursors, the results indicate that the structure and conformation of these substrates dictate where cleavage occurs. Furthermore, the data show that YAP3 has specificity for both monobasic and paired basic residues.