THE CONFORMATIONAL EFFECTS OF N-GLYCOSYLATION ON THE TAILPIECE FROM SERUM IGM
THE CONFORMATIONAL EFFECTS OF N-GLYCOSYLATION ON THE TAILPIECE FROM SERUM IGM
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DOI：
10.1111/j.1432-1033.1991.tb15995.x
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发表时间：
1991-05-23
期刊：
影响因子：
--
通讯作者：
DWEK, RA
中科院分区：
文献类型：
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作者：
WORMALD, MR;WOOTEN, EW;DWEK, RA
已使用H-1-NMR光谱来研究从人血清免疫球蛋白M分离的尾片段的构象和动力学，所述尾片段是含有单个天冬酰胺糖基化位点的22个残基的肽。 肽被分离为一组糖型，仅在糖基化位点连接的寡糖序列上不同。 存在的寡糖具有通式（Man）n（GlcNAc）2，其中45%具有n = 6，45%具有n = 8，10%具有n = 7和/或9。 他们已被确定和他们的NMR参数相比，发现在游离溶液中的分离寡糖。 的肽组分的构象和动力学也进行了研究，使用NOE数据和氢交换实验，并与从相同序列的无糖基肽获得的结果进行比较。 发现肽的存在对寡糖的构象没有可测量的影响。 然而，寡糖的存在导致糖基化位点区域中肽的主链和侧链的构象迁移率降低。 这被认为是寡糖核心和氨基酸侧链之间相互作用的结果。 此外，N-糖苷键的构象已被证明是刚性和平面的。 因此，糖蛋白中N-连接寡糖相对于蛋白质的构象空间可能在很大程度上取决于天冬酰胺侧链的柔性。 不同的糖型的尾肽的各种作用进行了讨论。
H-1-NMR spectroscopy has been used to study the conformation and dynamics of the isolated tailpiece from human serum immunoglobulin M, a 22-residue peptide containing a single asparagine glycosylation site. The peptide is isolated as a set of glycoforms, varying only in the sequence of the oligosaccharide attached at the glycosylation site. The oligosaccharides present have the general formula (Man)n(GlcNAc)2, with 45% having n = 6, 45% having n = 8 and 10% having n = 7 and/or 9. They have been identified and their NMR parameters compared to those found for the isolated oligosaccharides in free solution. The conformation and dynamics of the peptide component have also been studied, using NOE data and hydrogen-exchange experiments, and the results compared to those obtained from the aglycosyl peptide of the same sequence. The presence of the peptide is found to have no measurable effect on the conformation of the oligosaccharides. However, the presence of oligosaccharide causes a decrease in the conformational mobility of the backbone and sidechains of the peptide in the region of the glycosylation site. This is proposed to result from interactions between the oligosaccharide core and the amino acid side chains. Further, the conformation of the N-glycosidic linkage has been shown to be both rigid and planar. Thus, the conformational space available to an N-linked oligosaccharide in a glycoprotein relative to the protein may depend to a large extent upon the flexibility of the asparagine side chain. Various roles for the different glycoforms of the tail peptide are discussed.