DIPEPTIDYL PEPTIDASEIV, A KIDNEY BRUSH-BORDER SERINE PEPTIDASE
DIPEPTIDYL PEPTIDASEIV, A KIDNEY BRUSH-BORDER SERINE PEPTIDASE
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DOI：
10.1042/bj1570169
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发表时间：
1976-01-01
影响因子：
4.1
通讯作者：
YOUNG, AR
中科院分区：
文献类型：
--
作者：
KENNY, AJ;BOOTH, AG;YOUNG, AR
二肽基肽酶IV是一种从底物中释放二肽的酶，其N-末端序列为X-Pro-Y或X-Ala-Y，从猪肾皮质中纯化了300倍。肾脏是酶的主要来源，它是主要的微绒毛膜蛋白之一。其他几种组织对常用试验底物甘氨酰脯氨酸2-萘胺具有可证实的活性。在小肠中，这种活性在微绒毛组分中大大富集。在检查的所有组织中，活性对二异丙基氟磷酸酯（Dip-F）的抑制极其敏感，但对苯甲基磺酰氟的抑制相对耐受。它是一种丝氨酸蛋白酶，可以用[32 P]Dip-F共价标记，并且是微绒毛膜中唯一的此类酶。通过十二烷基硫酸钠/聚丙烯酰胺凝胶电泳和[32 P]Dip-F滴定估计的表观亚基MW为130，000。凝胶过滤和沉降平衡法得到的值在280，000的区域内，这与二聚体结构一致，纯化酶的EM支持这一结论。在其他特征良好的丝氨酸蛋白酶中，这种酶在其膜位置和大亚基大小方面是独特的。对肽酶对寡肽的攻击方式的研究表明，它可以水解某些N-封闭肽，例如，Z-Gly-Pro-Leu-Gly-Pro在这方面，它作为一种内肽酶，因此可能值得重新分类和重新命名为微绒毛膜丝氨酸肽酶。
Dipeptidyl peptidase IV, an enzyme that releases dipeptides from substrates with N-terminal sequences of the forms X-Pro-Y or X-Ala-Y, was purified 300-fold from pig kidney cortex. The kidney is the main source of the enzyme, where it is one of the major microvillus-membrane proteins. Several other tissues contained demonstrable activity against the usual assay substrate glycylproline 2-naphthylamide. In the small intestine this activity was greatly enriched in the microvillus fraction. In all tissues examined, the activity was extremely sensitive to inhibition by di-isopropyl phosphorofluoridate (Dip-F), but relatively resistant to inhibition by phenylmethylsulfonyl fluoride. It is a serine proteinase which may be covalently labeled with [32P]Dip-F, and is the only enzyme of this class in the microvillus membrane. The apparent subunit MW, estimated by sodium dodecylsulfate/polyacrylamide-gel electrophoresis and by titration with [32P]Dip-F, was 130,000. Gel filtration and sedimentation-equilibrium methods gave values in the region of 280,000, which is consistent with a dimeric structure, a conclusion supported by EM of the purified enzyme. Among other well-characterized serine proteinases, this enzyme is unique in its membrane location and its large subunit size. Investigation of the mode of attack of the peptidase on oligopeptides revealed that it could hydrolyze certain N-blocked peptides, e.g., Z-Gly-Pro-Leu-Gly-Pro. In this respect it is acting as an endopeptidase and as such may merit reclassification and renaming as microvillus-membrane serine peptidase.