Laidler P M, Waheed A, Van Etten R L
Institute of Medical Biochemistry, N. Copernicus Academy of Medicine, Kraków, Poland.
Acta Biochim Pol. 1988;35(4):343-56.
Homogeneous arylsulfatase A from human placenta, liver and urine contains two nonidentical subunits of 59 and 54 kDa. The two subunits are immunologically identical. The relative amount of low molecular weight subunits is only 20-30% of the total enzyme protein. Treatment of the enzyme under various conditions with endo-beta-N-acetylglucosaminidase F results in a decrease in the apparent molecular weight of both subunits by 1-2 kDa. a value that corresponds to the loss of a single N-linked oligosaccharide. However, as judged by carbohydrate staining, endo-beta-N-acetylglucosaminidase F does not remove all carbohydrate from the subunits or from glycopeptides of arylsulfatase A. In contrast, human prostatic acid phosphatase, a glycoprotein with a high content of mannose, hybrid and complex oligosaccharides is completely deglycosylated under identical experimental conditions. Several attempts to deglycosylate arylsulfatase A by chemical methods were unsuccessful due to poor recovery of the protein. From the present studies we conclude that arylsulfatase A contains an endo-beta-N-acetylglucosaminidase F resistant, perhaps O-linked carbohydrate.
来自人胎盘、肝脏和尿液的均一芳基硫酸酯酶A含有两个分子量分别为59 kDa和54 kDa的不同亚基。这两个亚基在免疫上是相同的。低分子量亚基的相对含量仅占总酶蛋白的20 - 30%。在各种条件下用内切β-N-乙酰氨基葡糖苷酶F处理该酶，会使两个亚基的表观分子量均降低1 - 2 kDa，这一数值对应于单个N-连接寡糖的丢失。然而，通过碳水化合物染色判断，内切β-N-乙酰氨基葡糖苷酶F并未从亚基或芳基硫酸酯酶A的糖肽中去除所有碳水化合物。相比之下，人前列腺酸性磷酸酶是一种含有高含量甘露糖、杂合和复合寡糖的糖蛋白，在相同实验条件下会被完全去糖基化。由于蛋白质回收率低，几次通过化学方法使芳基硫酸酯酶A去糖基化的尝试均未成功。从目前的研究中我们得出结论，芳基硫酸酯酶A含有一种对内切β-N-乙酰氨基葡糖苷酶F有抗性的、可能是O-连接的碳水化合物。
