Camarão G C, Carvalho K M, Cohen P
Departamento de Fisiologia e Farmacologia, Centro de Ciências da Saúde, Universidade Federal do Ceará, Fortaleza, CE, Brasil.
Braz J Med Biol Res. 1994 Dec;27(12):2863-7.
A multicatalytic proteinase complex present in the skin secretion of Xenopus laevis was purified and its enzymatic activity towards natural and synthetic peptides was investigated. We identified three activities: i) a C-terminal deamidation enzyme activity which exhibited selectivity for the Asp-Phe-NH2 and Phe-Leu-NH2 motifs of cerulein, minigastrin Leu-enkephalinamide, (des-Tyr1)Leu-enkephalinamide and diaminobenzylthiocyanate-DVDERDVRGFASFLNH2 (DABTC-DR8kermit); ii) an endopeptidase activity that cleaves peptide bonds on the carboxyl side of hydrophobic amino acid residues such as Tyr-Gly of LHRH, Ile-Ala of PGLa and Leu-Ala of buccalin; iii) an enzyme activity that cleaves peptide bonds at the dibasic sites of peptides of the dynorphin family. The molecular weight determined by Sephacryl S-400 molecular sieve filtration indicated an M(r) about 600 kDa. The activities characterized here exhibit an optimal pH of about 7.4. The activities of the multicatalytic complex were differentially inhibited by the classical inhibitors of proteases.
对非洲爪蟾皮肤分泌物中存在的一种多催化蛋白酶复合物进行了纯化，并研究了其对天然和合成肽的酶活性。我们鉴定出三种活性：i）一种C末端脱酰胺酶活性，对蛙皮素、迷你胃泌素亮氨酸脑啡肽酰胺、（去酪氨酸1）亮氨酸脑啡肽酰胺和二氨基苄基硫氰酸盐-DVDERDVRGFASFLNH2（DABTC-DR8克米特）的天冬氨酸-苯丙氨酸-NH2和苯丙氨酸-亮氨酸-NH2基序具有选择性；ii）一种内肽酶活性，可切割疏水性氨基酸残基羧基侧的肽键，如促性腺激素释放激素的酪氨酸-甘氨酸、PGLa的异亮氨酸-丙氨酸和颊肽的亮氨酸-丙氨酸；iii）一种酶活性，可在强啡肽家族肽的双碱性位点切割肽键。通过Sephacryl S-400分子筛过滤测定的分子量表明其Mr约为600 kDa。此处表征的活性表现出约7.4的最佳pH值。多催化复合物的活性受到蛋白酶经典抑制剂的不同抑制。
