Endo T, Radl J, Mestecky J
Department of Glycobiology, Tokyo Metropolitan Institute of Gerontology, Japan.
Mol Immunol. 1997 May;34(7):557-65. doi: 10.1016/s0161-5890(97)00070-9.
Asparagine-linked sugar chains were quantitatively released from chimpanzee, Rhesus monkey and rat IgA proteins as oligosaccharides by hydrazinolysis, converted to radioactive oligosaccharides by reduction with NaB3H4, and separated into neutral and two acidic fractions by paper electrophoresis. The acidic oligosaccharides were converted to neutral ones by sialidase digestion, indicating that they are sialyl derivatives. However, the content of N-acetyl and N-glycolyl neuraminic acids was different among three species. The neutral and sialidase-treated acidic oligosaccharides were fractionated by Bio-Gel P-4 column chromatography in combination with linkage-specific sequential exoglycosidase digestion. Although IgA molecules from these species have mainly biantennary complex-type sugar chains, the contents of fucose and bisecting N-acetylglucosamine residues displayed marked species differences. In addition to these sugar chains, a small amount of the high mannose-type sugar chains was detected in chimpanzee and rat, but not in Rhesus monkey IgA. These results indicated that the processing of asparagine-linked sugar chains of IgA is different in each species.
通过肼解作用，从黑猩猩、恒河猴和大鼠的IgA蛋白中定量释放出天冬酰胺连接的糖链，使其成为寡糖，用NaB3H4还原将其转化为放射性寡糖，并通过纸电泳将其分离为中性和两种酸性组分。酸性寡糖经唾液酸酶消化后转化为中性寡糖，表明它们是唾液酸衍生物。然而，三种物种中N-乙酰神经氨酸和N-羟乙酰神经氨酸的含量有所不同。通过Bio-Gel P-4柱色谱结合连接特异性顺序外切糖苷酶消化对中性和经唾液酸酶处理的酸性寡糖进行分级分离。尽管来自这些物种的IgA分子主要具有双天线复合型糖链，但岩藻糖和二分N-乙酰葡糖胺残基的含量存在明显的物种差异。除了这些糖链外，在黑猩猩和大鼠中检测到少量高甘露糖型糖链，而在恒河猴IgA中未检测到。这些结果表明，IgA中天冬酰胺连接糖链的加工在每个物种中都有所不同。
