Wu A M, Slomiany A, Herp A, Slomiany B L
Biochim Biophys Acta. 1979 Jun 19;578(2):297-304. doi: 10.1016/0005-2795(79)90160-0.
The structure of carbohydrate units of the major glycoprotein fraction of armadillo submandibular gland was investigated. Alkaline borohydride reductive cleavage of the glycoprotein resulted in the release of O-glycosidically linked mono- and disaccharide units. The monosaccharide was identified as N-acetylgalactosaminitol, whereas disaccharide contained of N-acetylneuraminic acid and N-acetylgalactosaminitol. Treatment of the native and desialyzed glycoprotein with alpha-N-acetylgalactosaminidase resulted in the removal of 60% and 96% of N-acetylgalactosamine, respectively. No cleavage of this sugar was affected by the action of beta-N-acetylhexosaminidase. Both N-acetylgalactosamine and N-acetylneuraminic acid were susceptible to oxidation with periodate. Analyses of the partially methylated N-acetylgalactosamine derivatives, obtained from the permethylated native glycoprotein, showed the presence of 3,4,6-tri-O-methyl-N-methylacetamidogalactose and 3,4-di-O-methyl-N-methylacetamidogalactose in a ratio of 1 : 0.4. Only 3,4,6-tri-O-methyl-N-methylacetamidogalactose was found in the hydrolysates of permethylated desialyzed glycoprotein. These results together with our previous data on chemical composition of the glycoprotein suggest that about 30% of the oligosaccharide chains consist of NeuAc alpha 2 leads to 6GalNAc alpha 1 leads to O-Thr(Ser) and 70% of GalNAc alpha leads to O-Thr(Ser).
对犰狳下颌下腺主要糖蛋白组分的碳水化合物单元结构进行了研究。糖蛋白经碱性硼氢化物还原裂解后，释放出O-糖苷键连接的单糖和二糖单元。单糖被鉴定为N-乙酰半乳糖胺醇，而二糖由N-乙酰神经氨酸和N-乙酰半乳糖胺醇组成。用α-N-乙酰半乳糖胺酶处理天然和去唾液酸糖蛋白，分别去除了60%和96%的N-乙酰半乳糖胺。β-N-乙酰己糖胺酶的作用不影响该糖的裂解。N-乙酰半乳糖胺和N-乙酰神经氨酸都易被高碘酸盐氧化。对从全甲基化天然糖蛋白获得的部分甲基化N-乙酰半乳糖胺衍生物的分析表明，3,4,6-三-O-甲基-N-甲基乙酰氨基半乳糖和3,4-二-O-甲基-N-甲基乙酰氨基半乳糖的比例为1:0.4。在全甲基化去唾液酸糖蛋白的水解产物中仅发现3,4,6-三-O-甲基-N-甲基乙酰氨基半乳糖。这些结果与我们之前关于糖蛋白化学组成的数据一起表明，约30%的寡糖链由NeuAcα2→6GalNAcα1→O-Thr(Ser)组成，70%由GalNAcα→O-Thr(Ser)组成。
