Ben-Yoseph Y, Hungerford M, Nadler H L
Biochem J. 1980 Jul 1;189(1):9-15. doi: 10.1042/bj1890009.
Galactocerebrosidase (beta-d-galactosyl-N-acylsphingosine galactohydrolase; EC 3.2.1.46) activity of brain and liver preparations from normal individuals and patients with Krabbe disease (globoid-cell leukodystrophy) have been separated by gel filtration into four different molecular-weight forms. The apparent mol.wts. were 760000+/-34000 and 121000+/-10000 for the high- and low-molecular-weight forms (peaks I and IV respectively) and 499000+/-22000 (mean+/-s.d.) and 256000+/-12000 for the intermediate forms (peaks II and III respectively). On examination by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, the high- and low-molecular-weight forms revealed a single protein band with a similar mobility corresponding to a mol.wt. of about 125000. Antigenic identity was demonstrated between the various molecular-weight forms of the normal and the mutant galactocerebrosidases by using antisera against either the high- or the low-molecular-weight enzymes. The high-molecular-weight form of galactocerebrosidase was found to possess higher specific activity toward natural substrates when compared with the low-molecular-weight form. It is suggested that the high-molecular-weight enzyme is the active form in vivo and an aggregation process that proceeds from a monomer (mol.wt. approx. 125000) to a dimer (mol.wt. approx. 250000) and from the dimer to either a tetramer (mol.wt. approx. 500000) or a hexamer (mol.wt. approx. 750000) takes place in normal as well as in Krabbe-disease tissues.
已通过凝胶过滤法将正常个体和克拉伯病（球形细胞脑白质营养不良症）患者的脑和肝制剂中的半乳糖脑苷脂酶（β - d - 半乳糖基 - N - 酰基鞘氨醇半乳糖水解酶；EC 3.2.1.46）活性分离为四种不同分子量形式。高分子量和低分子量形式（分别为峰I和峰IV）的表观分子量分别为760000±34000和121000±10000，中间形式（分别为峰II和峰III）的表观分子量为499000±22000（平均值±标准差）和256000±12000。经十二烷基硫酸钠/聚丙烯酰胺凝胶电泳检测，高分子量和低分子量形式均显示出一条迁移率相似的单一蛋白带，对应分子量约为125000。通过使用针对高分子量或低分子量酶的抗血清，证明了正常和突变半乳糖脑苷脂酶的各种分子量形式之间存在抗原同一性。与低分子量形式相比，发现半乳糖脑苷脂酶的高分子量形式对天然底物具有更高的比活性。有人提出，高分子量酶是体内的活性形式，在正常组织以及克拉伯病组织中都发生了从单体（分子量约125000）到二聚体（分子量约250000），再从二聚体到四聚体（分子量约500000）或六聚体（分子量约750000）的聚集过程。
