| 摘要 |
<p>A novel leucine aminopeptidase having the following properties: (a) action and substrate specificity: (1) having an activity of decomposing a synthetic substrate, L-leucine P-nitroanilide, characterized by having a methionine resistance, (2) having a cystine aminopeptidase activity, and (3) having an activity of decomposing at least oxytocin, vasopressin and angiotensin III, among naturally occurring hormones; (b) optimum pH and stable pH range: having the optimum pH around a neutral region (at a pH of about 7.4); (c) condition of deactivation by pH, temperature, etc.: being deactivated at 70 °C in 30 minutes; (d) inhibition, activation and stabilization: being deactivated by a divalent metallic ion such as Zn?2+, Co2+ or Ni2+¿; (e) molecular weight: having a molecular weight of about 490 kDa (according to gel filtration), while that of the subunit being about 210 kDa (according to SDS-PAGE) (no difference in mobility observed between reducing and nonreducing conditions); (f) sequence number: having the following amino acid sequences represented by 1, 2, 3 and 4: Gly Trp Gly Leu Gly Lys; Leu Leu Gln Asn Gln Ile Gln Gln Gln Thr Arg Thr Asp Glu Gly Thr Pro; Thr Asp Lys Gly Trp Ser Phe Leu Leu Gly Lys; Phe Phe Leu Asn Met Lys Pro Glu Ile Gln Pro Gln Asp; (g) purification: being purified from the human retroplacental blood after eutocia.</p> |
