法布里半合子组织中残余α-半乳糖苷酶活性的特性

Properties of the residual alpha-galactosidase activity in the tissues of a Fabry hemizygote.

作者信息

Rietra P J, Van den Bergh F A, Tager J M

出版信息

Clin Chim Acta. 1975 Aug 4;62(3):401-13. doi: 10.1016/0009-8981(75)90092-3.

Abstract

The properties of the residual alpha-galactosidase activity in kidney, liver, spleen, fibroblasts and urine of a Fabry hemizygote have been studied using p-nitrophenyl-alpha-galactoside and 4-methylumbelliferyl-alpha-galactoside as substrates. In addition, alpha-galactosidase activity in urine has been determined with ceramidetrihexoside as substrate. The residual alpha-galactosidase activity of Fabry, measured with artificial substrate, is stimulated (6-35%) by myo-inositol and only slightly inhibited by melibiose (7-17%) in all the materials used. In contrast, the alpha-galactosidase of normal tissues and urine is inhibited (36-48%) by myo-inositol and inhibited to a much greater extent (40-50%) by melibiose. The KM for artificial substrate of the residual activity of Fabry is higher than that of the alpha-galactosidase in normal kidney, liver, spleen, fibroblasts and urine. The residual activity of Fabry is generally more stable to heating than the activity in the normal materials, although exceptions were noted. When these properties are compared with those of the alpha-galactosidase isoenzymes in normal tissues and body fluids, the residual activity of Fabry material seems to be very similar to the minor component of normal tissue (alpha-galactosidase B). Moreover, the pH optimum curve of this minor component and of the Fabry alpha-galactosidase in urine are similar, whereas the major isoenzyme (alpha-galactosidase A) shows a curve much more like that of normal urine. The findings with ceramidetrihexoside as substrate indicate a possible discrepancy. Alpha-Galactosidase A hydrolyses ceramidetrihexoside, Fabry urine preparation does not. However, alpha-galactosidase B of normal urine shows a slight but definite ceramidetrihexosidase activity. No contamination of the B preparation with alpha-galactosidase A could be detected. The minimum hypothesis, supported by most of the experimental evidence, is that the residual activity of Fabry and normal alpha-galactosidase B are identical.

摘要

利用对硝基苯基 -α- 半乳糖苷和4 - 甲基伞形酮基 -α- 半乳糖苷作为底物，研究了法布里（Fabry）半合子的肾脏、肝脏、脾脏、成纤维细胞和尿液中残余α- 半乳糖苷酶活性的特性。此外，还以神经酰胺三己糖苷作为底物测定了尿液中的α- 半乳糖苷酶活性。用人工底物测定时，法布里病患者的残余α- 半乳糖苷酶活性在所有使用的材料中均受到肌醇的刺激（6% - 35%），仅受到蜜二糖的轻微抑制（7% - 17%）。相比之下，正常组织和尿液中的α- 半乳糖苷酶受到肌醇的抑制（36% - 48%），受到蜜二糖的抑制程度更大（40% - 50%）。法布里病患者残余活性的人工底物的米氏常数（KM）高于正常肾脏、肝脏、脾脏、成纤维细胞和尿液中的α- 半乳糖苷酶。尽管有例外情况，但法布里病患者的残余活性通常比正常材料中的活性对加热更稳定。当将这些特性与正常组织和体液中的α- 半乳糖苷酶同工酶的特性进行比较时，法布里病材料的残余活性似乎与正常组织的次要成分（α- 半乳糖苷酶B）非常相似。此外，尿液中这种次要成分和法布里病患者α- 半乳糖苷酶的最适pH曲线相似，而主要同工酶（α- 半乳糖苷酶A）的曲线更类似于正常尿液的曲线。以神经酰胺三己糖苷作为底物的研究结果表明可能存在差异。α- 半乳糖苷酶A可水解神经酰胺三己糖苷，而法布里病患者的尿液制剂则不能。然而，正常尿液中的α- 半乳糖苷酶B表现出轻微但确定的神经酰胺三己糖苷酶活性。未检测到B制剂被α- 半乳糖苷酶A污染。大多数实验证据支持的最小假设是，法布里病患者的残余活性与正常α- 半乳糖苷酶B相同。