Parodi A J, Quesada Allue L A, Cazzulo J J
Proc Natl Acad Sci U S A. 1981 Oct;78(10):6201-5. doi: 10.1073/pnas.78.10.6201.
Cells of the insect parasite Crithidia fasciculata incubated with [14C]glucose were found to possess only one lipid-bound oligosaccharide with solubility in chloroform/methanol/water mixtures and net charge similar to the charges of dolichol pyrophosphate derivatives. The saccharide moiety could be released from lipid by mild acid hydrolysis. Several enzymatic and chemical treatments of the oligosaccharide indicated that the latter had the structure Man alpha leads to Man alpha leads to Man alpha leads to [Man alpha leads to Man alpha leads to Man (alpha 1 leads to 6)]Man leads to GlcNAc(beta 1 leads to 4)GlcNAc. Two labeled oligosaccharides were liberated from proteins by a sequential treatment with a protease and endo-beta-N-acetylglucosamindase H. One of the protein-bound oligosaccharides had the same structure as the lipid-linked compound, whereas in the second oligosaccharide some mannose residues had been replaced by galactose units, but both compounds migrated as did a Man7GlcNAc standard. These were the largest oligosaccharides obtained even after short labeling periods. It is suggested that glycosylation of proteins in the protozoan Crithidia fasciculata does not involved glucosylated lipid-bound oligosaccharides as intermediates.
用[14C]葡萄糖孵育昆虫寄生虫 fasciculata 的细胞后发现，其仅有一种与脂质结合的寡糖，可溶于氯仿/甲醇/水混合物，且净电荷与焦磷酸多萜醇衍生物的电荷相似。糖部分可通过温和的酸水解从脂质中释放出来。对该寡糖进行的几种酶促和化学处理表明，其结构为 Manα→Manα→Manα→[Manα→Manα→Man(α1→6)]Man→GlcNAc(β1→4)GlcNAc。通过蛋白酶和内切β-N-乙酰葡糖胺酶 H 依次处理，从蛋白质中释放出两种标记的寡糖。其中一种与蛋白质结合的寡糖与脂质连接的化合物结构相同，而在第二种寡糖中，一些甘露糖残基已被半乳糖单元取代，但这两种化合物的迁移情况与 Man7GlcNAc 标准品相同。即使在短时间标记后，这些也是获得的最大寡糖。有人提出，原生动物 fasciculata 中蛋白质的糖基化不涉及糖基化的脂质结合寡糖作为中间体。
