Mikhaylova M, Wiederschain G, Mikhaylov V, Aerts J M
Laboratory of Carbohydrate Chemistry, Institute of Biomedical Chemistry, Russian Academy of Medical Sciences, Moscow, Russia.
Biochim Biophys Acta. 1996 Oct 7;1317(1):71-9. doi: 10.1016/0925-4439(96)00040-3.
Fluorogenic 6-acylamino-4-methylumbelliferyl-beta-D-glucosides were found to be poor substrates for the three known human beta-glucosidases, i.e., lysosomal and non-lysosomal glucocerebrosidases and cytosolic broad-specificity beta-glucosidase. However, homogenates of human tissues and human cell types showed significant enzymatic hydrolysis of 6-ethanoylamino-4-methylumbelliferyl-beta-D-glucoside (EMGlc) due to the activity of a hitherto undescribed beta-glucosidase, called here EMGlc-ase. It was shown that the isozyme is hardly active towards 4-methylumbelliferyl-beta-D-glucoside or glucosylceramide. EMGlc-ase exhibits maximal activity at pH 4.5 and 5.0 in the absence and presence of sodium taurocholate respectively. It is a soluble lysosomal enzyme with a discrete isoelectric point of about 5.0. EMGlc-ase is not inhibited by conduritol B-epoxide, is activated by sodium taurocholate and binds strongly to Concanavalin A. This enzyme is not deficient in relation to Gaucher disease.
荧光6-酰基氨基-4-甲基伞形酮基-β-D-葡萄糖苷被发现是三种已知人类β-葡萄糖苷酶的不良底物，即溶酶体和非溶酶体葡糖脑苷脂酶以及胞质广谱β-葡萄糖苷酶。然而，由于一种迄今未描述的β-葡萄糖苷酶（在此称为EMGlc酶）的活性，人类组织和人类细胞类型的匀浆显示出对6-乙酰氨基-4-甲基伞形酮基-β-D-葡萄糖苷（EMGlc）的显著酶促水解。结果表明，该同工酶对4-甲基伞形酮基-β-D-葡萄糖苷或葡糖神经酰胺几乎没有活性。EMGlc酶在不存在和存在牛磺胆酸钠的情况下，分别在pH 4.5和5.0时表现出最大活性。它是一种可溶性溶酶体酶，其离散的等电点约为5.0。EMGlc酶不受conduritol B-环氧化物抑制，被牛磺胆酸钠激活，并与伴刀豆球蛋白A强烈结合。这种酶在戈谢病方面并不缺乏。
