PROTEINS OF THE KIDNEY MICROVILLAR MEMBRANE - ENZYMATIC AND MOLECULAR-PROPERTIES OF AMINOPEPTIDASE-W
PROTEINS OF THE KIDNEY MICROVILLAR MEMBRANE - ENZYMATIC AND MOLECULAR-PROPERTIES OF AMINOPEPTIDASE-W
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DOI：
10.1042/bj2460097
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发表时间：
1987-08-15
影响因子：
4.1
通讯作者：
KENNY, AJ
中科院分区：
文献类型：
--
作者：
GEE, NS;KENNY, AJ
氨基肽酶W是一种新发现的存在于肾脏和肠道刷状边界的酶，首次被分离为130 kDa的糖蛋白，并被单克隆抗体识别[Gee and Kenny (1985) Biochem]。[j].科学通报，2003,18(4):444 - 444。它在二肽的水解中特别有效，Glu-Trp （Km 0.57 mM; kcat 6770 min-1）是一个有利的底物。在P1位置有色氨酸、苯丙氨酸或酪氨酸的二肽可以快速水解，但对P1残基的要求不严格。氨基肽酶W的活性受离子条件的显著影响。100 mM-Tris/HCl， pH为8时活性最高；磷酸盐离子具有很强的抑制作用。二价金属离子对活性的影响也很大，影响的大小和方向取决于缓冲阴离子的性质和ph。最有效的抑制剂是阿马伐他汀和百司他汀。一些硫醇被抑制，但其他螯合剂，EDTA和1,10-菲罗啉，在1-10毫米的浓度范围内没有作用。其他类群特异性抑制剂，如半胱氨酸、丝氨酸或天冬氨酸肽酶，也无效。研究了一些分子性质。用n -聚糖酶处理去糖基化使表观亚基Mr从130000降低到90000。该酶含有锌，1.2个原子/亚基，尽管该酶在螯合剂方面具有非典型的性质，但锌催化机制是最有可能的。它在消化和肾功能中的作用尚不清楚。
Aminopeptidase W is a newly discovered enzyme of the renal and intestinal brush borders, having been first isolated as a 130 kDa glycoprotein recognized by a monoclonal antibody [Gee and Kenny (1985) Biochem. J. 230, 753-764]. It is particularly effective in the hydrolysis of dipeptides, Glu-Trp (Km 0.57 mM; kcat 6770 min-1) being a favoured substrate. Dipeptides with tryptophan, phenylalanine or tyrosine in the P1 position were rapidly hydrolysed, but the requirements in respect of the P1 residue were not stringent. The activity of aminopeptidase W is markedly influenced by ionic conditions. The highest activity was observed in 100 mM-Tris/HCl, pH 8; phosphate ions were strongly inhibitory. Activity was also greatly affected by bivalent metal ions, and the magnitude and direction of the effects depended on the nature of the buffer anions and on pH. The most effective inhibitors were amastatin and bestatin. Some thiols are inhibited, but other chelating agents, EDTA and 1,10-phenanthroline, had no effect over the concentration range 1-10 mM. Other group-specific inhibitors, for cysteine, serine or aspartic peptidases, were also ineffective. Some molecular properties were studied. Deglycosylation by treatment with N-glycanase diminished the apparent subunit Mr from 130000 to 90000. The enzyme contained zinc, 1.2 atoms/subunit, and in spite of the atypical properties of this enzyme in respect of chelating agents, a zinc-catalysed mechanism is the most probable. Its roles in digestion and a renal function are not yet clear.