Reinhold B B, Hauer C R, Plummer T H, Reinhold V N
Department of Nutrition, Harvard University School of Public Health, Boston, Massachusetts 02115, USA.
J Biol Chem. 1995 Jun 2;270(22):13197-203. doi: 10.1074/jbc.270.22.13197.
In the preceding paper, preliminary analysis revealed a new type of O-linked oligosaccharide of 1244 Da at each of two proposed glycosylation sites on several proteins secreted by the Gram-negative bacterium Flavobacterium meningosepticum (Plummer, T. H., Jr., Tarentino, A. L., and Hauer, C. R. (1995) J. Biol. Chem. 270, 13192-13196). In this report we detail the linkage, sequence, and branching of this unusual heptasaccharide by electrospray (ES) ionization mass spectrometry (MS), and collision-induced dissociation (CID). The proposed structure was supported by a combination of isotopic labeling, composition and methylation analysis, and the preparation of several chemical analogs and derivatives with each product evaluated by MS and CID. The singly branched structure contained seven residues, including three different uronyl analogs: a methylated rhamnose and mannose, a glucose, and a reducing terminal mannose. Only pyranose ring forms were detected ((2-OMe)Man1-4GlcNAcU1-4GlcU1-4Glc1-4(2-OMe)G lcU-4 [(2-OMe)Rham1-2]Man).
在前一篇论文中，初步分析揭示了在革兰氏阴性菌脑膜败血黄杆菌分泌的几种蛋白质上的两个假定糖基化位点处，均存在一种分子量为1244 Da的新型O-连接寡糖（Plummer, T. H., Jr., Tarentino, A. L., and Hauer, C. R. (1995) J. Biol. Chem. 270, 13192 - 13196）。在本报告中，我们通过电喷雾（ES）电离质谱（MS）和碰撞诱导解离（CID）详细阐述了这种不寻常的七糖的连接方式、序列和分支情况。所提出的结构得到了同位素标记、组成和甲基化分析的组合支持，以及几种化学类似物和衍生物的制备，每种产物均通过MS和CID进行评估。单分支结构包含七个残基，包括三种不同的糖醛酸类似物：一个甲基化的鼠李糖和甘露糖、一个葡萄糖以及一个还原端甘露糖。仅检测到吡喃糖环形式（(2 - OMe)Man1 - 4GlcNAcU1 - 4GlcU1 - 4Glc1 - 4(2 - OMe)GlcU - 4 [(2 - OMe)Rham1 - 2]Man）。
