Beratis N G, LaBadie G U, Hirschhorn K
J Clin Invest. 1978 Dec;62(6):1264-74. doi: 10.1172/JCI109247.
Different clinical expressions of acid alpha-glucosidase deficiency have been described. The present study was undertaken to investigate the basic metabolic defect in the infantile and adult forms of the disease. Acid alpha-glucosidase (EC 3.2.1.20) was purified from normal and from adult acid alpha-glucosidase deficiency fibroblasts. The pH optimum; Michaelis constant; electrophoretic mobility in starch; thermal denaturation at pH 4.0 and 7.0; and inhibition by turanose, alpha-methylglucoside and trehalose were the same in purified enzyme from normal and mutant cells. Placental acid alpha-glucosidase was purified to, or near, homogeneity. Monospecific antibodies raised against the enzyme in each of three enzyme peaks obtained from the last purification step were found to cross-react with the enzyme of all three peaks, and with purified, normal fibroblast enzyme. Cross-reacting material (CRM) also was identified in fibroblast lysates from normal subjects and from both forms of acid alpha-glucosidase deficiency. The amount of CRM in the adult form appeared to be significantly less than in normal cells or cells from the infantile form. Enzyme activity was demonstrated in the immune complexes of the normal and adult acid alpha-glucosidase deficiency fibroblasts, but not of the infantile form. Competition for antibody binding sites was observed between normal and both types of mutant enzymes. The findings indicate that this case of infantile acid alpha-glucosidase deficiency is the result of a structural gene mutation which causes the synthesis of a catalytically inactive (CRM-positive) enzyme protein. It appears that in the adult form, the mutation causes a reduction in the amount of the enzyme protein present in the cells.
已描述了酸性α-葡萄糖苷酶缺乏症的不同临床表型。本研究旨在调查该疾病婴儿型和成人型的基本代谢缺陷。从正常和成人性酸性α-葡萄糖苷酶缺乏症的成纤维细胞中纯化酸性α-葡萄糖苷酶（EC 3.2.1.20）。正常细胞和突变细胞纯化酶的最适pH值、米氏常数、在淀粉中的电泳迁移率、在pH 4.0和7.0下的热变性以及被松二糖、α-甲基葡萄糖苷和海藻糖的抑制作用均相同。胎盘酸性α-葡萄糖苷酶被纯化至接近均一性。针对从最后纯化步骤获得的三个酶峰中的每一个峰中的酶产生的单特异性抗体，被发现与所有三个峰的酶以及纯化的正常成纤维细胞酶发生交叉反应。在正常受试者以及两种酸性α-葡萄糖苷酶缺乏症形式的成纤维细胞裂解物中也鉴定出了交叉反应物质（CRM）。成人型中CRM的量似乎明显少于正常细胞或婴儿型细胞中的量。在正常和成人性酸性α-葡萄糖苷酶缺乏症成纤维细胞的免疫复合物中检测到酶活性，但婴儿型中未检测到。观察到正常酶与两种突变酶之间存在对抗体结合位点的竞争。这些发现表明，该婴儿型酸性α-葡萄糖苷酶缺乏症病例是结构基因突变的结果，该突变导致催化无活性（CRM阳性）的酶蛋白的合成。似乎在成人型中，该突变导致细胞中存在的酶蛋白量减少。
