Alkaline phosphatase of basal lateral and brush border plasma membranes from intestinal epithelium.
Alkaline phosphatase of basal lateral and brush border plasma membranes from intestinal epithelium.
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来自肠上皮的基底外侧和刷状缘质膜的碱性磷酸酶。
DOI：
10.1002/jss.400110404
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发表时间：
1979
期刊：
影响因子：
--
通讯作者：
E. M. Wright
中科院分区：
文献类型：
--
作者：
S. Hanna;A. Mircheff;E. M. Wright
本文用多种生化方法和物理方法检测了大鼠十二指肠上皮刷状缘和基侧膜上的碱性磷酸酶。这两种碱性磷酸酶具有相似的最适pH为9.6-9.8，相似的底物Km为71微摩尔的对硝基苯磷酸(PNPP)，对2-巯基乙醇、茶碱、苯丙氨酸和乙二胺四乙酸(EDTA)的反应相似，对钙、镁、锌、钠和钾的敏感度相似，对木瓜酶的胰酶消化不敏感。这两种酶在十二烷基硫酸钠-聚丙烯酰胺凝胶上的相对分子质量也相似，在124,000-150,000范围内，两种酶在Triton X-100聚丙烯酰胺凝胶上的Rf值都为0.092，表明两种酶的本征电荷相似。刷状边缘酶的Vmax是基础侧链酶的10倍，为140mg.h，而不是14mg.h。Vmax的差异反映了已知的碱性磷酸酶在大鼠十二指肠中的分布，刷状缘的碱性磷酸酶比基底面的碱性磷酸酶活性更高。观察到两种酶之间的另一个主要区别是，十二烷基硫酸钠、Triton X-100或胆酸盐对碱性磷酸酶的刺激作用是基侧的，而不是刷状边缘的。我们得出的结论是，这些酶彼此非常相似，可能具有相似的膜功能。
The alkaline phosphatase present on isolated brush border and basal lateral membranes of rat duodenal epithelium were examined by means of a variety of biochemical assays and physical methods. The two alkaline phosphatases have similar pH optima of 9.6--9.8, similar substrate km's for p-nitrophenyl phosphate (PNPP) of 71 micromolar, similar responses to the inhibitors 2-mercaptoethanol, theophylline, phenylalanine, and ethylenediaminetetraacetic acid (EDTA), similar sensitivities to calcium, magnesium, zinc, sodium, and potassium, and similar insensitivities to digestion with trypsin of papain. The two enzymes also exhibit similar molecular weights on SDS-polyacrylamide gels in the range 124,000--150,000, and both enzymes show an Rf value of 0.092 on Triton X-100 polyacrylamide gels, indicating similar intrinsic charges. The Vmax of the brush border enzyme is ten times greater than that of the basal lateral enzyme, 140 mumoles/mg-h as opposed to 14 mumoles/mg-h. The differences in Vmax are a reflection of the known distribution of alkaline phosphatase in rat duodenum, there being more alkaline phosphatase activity present on the brush border than on the basal lateral surface. One other major difference was observed between the two enzymes, the stimulation of the basal lateral and not the brush border alkaline phosphatase by SDS, Triton X-100, or cholate. We conclude that the enzymes are very similar to one another and probably perform similar membrane functions.