Foulon T, Cadel S, Prat A, Chesneau V, Hospital V, Segrétain D, Cohen P
Laboratoire de Biochimie des Signaux Régulateurs Cellulaires et Moléculaires, Université Pierre et Marie-Curie, Paris, France.
Ann Endocrinol (Paris). 1997;58(5):357-64.
An endoprotease and an aminopeptidase B were isolated from rat testis and characterized. The first one is a metalloendopeptidase of 1161 residues which contains a canonical HXXEHX76E Zn(2+)-binding site and an acidic stretch of 71 amino acids containing 79% of Glu and Asp. It exhibits an in vitro selectivity for peptide bonds at the N-terminus of Arg (R) moieties in dibasic sites and was thus called NRD convertase (Nardilysin: EC 3.4.24.61). It belongs to the pitrilysin family and shows 24 and 34% identity with E. coli protease III (EC 3.4.24.54) and insulysin (EC 3.4.24.55) respectively. The aminopeptidase B component is a 72 kDa metalloexopeptidase which is able to remove Lys and Arg residues from naphtylamide derivatives and from the N-terminus of various peptide substrates. A combination of biochemical and immunochemical studies revealed its ubiquitous character. In the testis, both enzymes are highly expressed at late stages of spermatogenesis and NRD convertase expression is exclusively restricted to the germ cells. The subcellular localization of both enzymes supports the involvement of aminopeptidase B in processing events associated with the secretory pathway but led to new hypothesis on the possible physiological role(s) of NRD convertase.
从大鼠睾丸中分离并鉴定了一种内切蛋白酶和一种氨肽酶B。第一种是一种含1161个残基的金属内切蛋白酶，它含有一个典型的HXXEHX76E锌离子结合位点和一段由71个氨基酸组成的酸性序列，其中谷氨酸（Glu）和天冬氨酸（Asp）占79%。它在体外对双碱性位点中精氨酸（R）残基N端的肽键具有选择性，因此被称为NRD转化酶（nardilysin：EC 3.4.24.61）。它属于pitrilysin家族，与大肠杆菌蛋白酶III（EC 3.4.24.54）和胰岛素酶（EC 3.4.24.55）的同源性分别为24%和34%。氨肽酶B成分是一种72 kDa的金属外切蛋白酶，能够从萘酰胺衍生物和各种肽底物的N端去除赖氨酸和精氨酸残基。生化和免疫化学研究相结合揭示了其普遍存在的特性。在睾丸中，这两种酶在精子发生后期均高度表达，且NRD转化酶的表达仅局限于生殖细胞。这两种酶的亚细胞定位支持氨肽酶B参与与分泌途径相关的加工过程，但也引发了关于NRD转化酶可能的生理作用的新假说。
