Vaccaro A M, Muscillo M, Tatti M, Salvioli R, Gallozzi E, Suzuki K
Laboratory of Metabolism and Pathological Biochemistry, Istituto Superiore di Sanità, Roma, Italy.
Clin Biochem. 1987 Dec;20(6):429-33. doi: 10.1016/0009-9120(87)90010-5.
A new protein activator of glucosylceramidase has recently been found in human placenta. In the present work, it has been compared with a previously reported glucosylceramidase activator, the Gaucher factor. The two activators showed different properties. The Gaucher factor stimulated 100% the 4-methylumbelliferyl-beta-D-glucopyranoside hydrolysis while the placental factor inhibited it 50%. Furthermore, the placental factor neither decreased the Michaelis constant, Km, nor increased the degree of inactivation by conduritol-beta-epoxide as the Gaucher factor does. From these results it has been concluded that the two activators are different substances. The activating effect of the placental factor is specific for the hydrolysis of glucosylceramide; neither the hydrolysis of glucosylsphingosine nor that of the 4-methylumbelliferyl derivative are enhanced by this protein. Owing to its specificity and high level in a human tissue, the placental factor is likely to have a physiological role in the catabolism of glucosylceramide.
最近在人胎盘中发现了一种新的葡糖神经酰胺酶蛋白激活剂。在本研究中，将其与先前报道的葡糖神经酰胺酶激活剂——高雪因子进行了比较。这两种激活剂表现出不同的特性。高雪因子可使4-甲基伞形酮基-β-D-吡喃葡萄糖苷水解增加100%，而胎盘因子则抑制其50%。此外，胎盘因子既不像高雪因子那样降低米氏常数（Km），也不会增加伴刀豆球蛋白-β-环氧化物的失活程度。从这些结果可以得出结论，这两种激活剂是不同的物质。胎盘因子的激活作用对葡糖神经酰胺的水解具有特异性；该蛋白既不增强葡糖神经鞘氨醇的水解，也不增强4-甲基伞形酮衍生物的水解。由于其特异性以及在人体组织中的高含量，胎盘因子可能在葡糖神经酰胺的分解代谢中具有生理作用。
