AMINOPEPTIDASE-B IN THE RAT TESTES - ISOLATION, FUNCTIONAL-PROPERTIES AND CELLULAR-LOCALIZATION IN THE SEMINIFEROUS TUBULES
AMINOPEPTIDASE-B IN THE RAT TESTES - ISOLATION, FUNCTIONAL-PROPERTIES AND CELLULAR-LOCALIZATION IN THE SEMINIFEROUS TUBULES
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DOI：
10.1016/0303-7207(95)03529-g
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发表时间：
1995-04-28
影响因子：
4.1
通讯作者：
COHEN, P
中科院分区：
文献类型：
--
作者：
CADEL, S;PIEROTTI, AR;COHEN, P
从大鼠睾丸中分离出一种B型氨肽酶，其表观M（r）为72000，pI = 4.9。该酶能够从L-氨基酸β-萘酰胺衍生物和几种肽的N-末端仅去除Arg和/或Lys残基。在缓激肽和P物质中发现的Arg-Pro键的情况下没有发生裂解。该酶对半胱氨酰试剂和氨肽酶抑制剂（如bestatin、amastatin和arphamenines A和B）敏感。用L-Arg β-萘酰胺和Arg（0）-甲硫脑啡肽作为底物测试的氨肽酶活性被邻菲咯啉抑制，并被Zn 2+恢复，表明其具有金属肽酶特征。在大鼠大脑皮层的氨肽酶-B活性的部分表征确定了一种蛋白质，这是生化和免疫相关的睾丸酶。通过免疫组化，氨肽酶-B被发现是特别丰富的曲细精管在精子发生的后期阶段，并清楚地检测到在一个有限的区域延长精子细胞。值得注意的是，酶被观察到大量集中在残留体中。由于这种氨肽酶-B能够在体外修剪N-末端精氨酸和/或赖氨酸残基肽模仿加工中间体，它建议，这种酶可能参与前肽和前蛋白加工机制的过程中的精子细胞分化。
An aminopeptidase of the B-type, with an apparent M(r) 72 000 and pI = 4.9, was isolated from rat testes and characterized. The enzyme was able to remove only Arg and/or Lys residues from L-amino acid beta-naphthylamide derivatives and from the N-terminus of several peptides. No cleavage occurred in the case of Arg-Pro bonds as found in bradykinin and substance P. The enzyme was sensitive to cysteinyl reagents and to aminopeptidase inhibitors, such as bestatin, amastatin and arphamenines A and B. The aminopeptidase activity, tested with L-Arg beta-naphthylamide and with Arg(0)-Met-enkephalin as substrates, was inhibited by o-phenanthroline, and restored by Zn2+ suggesting its metallopeptidase character. The partial characterization of an aminopeptidase-B activity in rat brain cortex identified a protein which is biochemically and immunologically related to the testis enzyme. By immunohistochemistry, the aminopeptidase-B was found to be particularly abundant in the seminiferous tubules at late stages of spermatogenesis and was clearly detected in a restricted area of elongated spermatids. Remarkably, the enzyme was observed to concentrate massively in the residual bodies. Since this aminopeptidase-B was able in vitro to trim out N-terminal Arg and/or Lys residues from peptides mimicking processing intermediates, it is proposed that this enzyme may be involved in propeptide and proprotein processing mechanisms in the course of spermatid differentiation.