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>Structural analysis of colanic acid from Escherichia coli by using methylation and base-catalysed fragmentation. Comparison with polysaccharides from other bacterial sources
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Structural analysis of colanic acid from Escherichia coli by using methylation and base-catalysed fragmentation. Comparison with polysaccharides from other bacterial sources
pEssentially the same methanolysis products were obtained after methylation of the slime and capsular polysaccharides from iEscherichia coli/i K12 (S53 and S53C sub-strains) and the slime polysaccharides from iE. coli/i K12 (S61), iAerobacter cloacae/i N.C.T.C. 5290 and iSalmonella typhimurium/i SL1543. These were the methyl glycosides of 2-iO/i-methyl-l-fucose, 2,3-di-iO/i-methyl-l-fucose, 2,3-di-iO/i-methyl-d-glucuronic acid methyl ester, 2,4,6-tri-iO/i-methyl-d-glucose, 2,4,6-tri-iO/i-methyl-d-galactose and the pyruvic acid ketal, 4,6-iO/i-(1′-methoxycarbonylethylidene)-2,3-iO/i-methyl-d-galactose. All were identified as crystalline derivatives from an iE. coli/i polysaccharide. The structure of the ketal was proved by proton-magnetic-resonance and mass spectrometry, and by cleavage to pyruvic acid and 2,3-di-iO/i-methyl-d-galactose. All these polysaccharides are therefore regarded as variants on the same fundamental structure for which the name colanic acid is adopted. Although containing the same sugar residues, quite different methanolysis products were obtained after methylation of the extracellular polysaccharide from iKlebsiella aerogenes/i (1.2 strain). The hydroxypropyl ester of iE. coli/i polysaccharide, when treated with base under anhydrous conditions, underwent β-elimination at the uronate residues with release of a 4,6-iO/i-(1′-alkoxycarbonylethylidene)-d-galactose. Together with the identification of 3-iO/i-(d-glucopyranosyluronic acid)-d-galactose as a partial hydrolysis product, this establishes the nature of most, if not all, of the side chains as iO/i-[4,6-iO/i-(1′-carboxyethylidene)-d-galactopyranosyl]-(1→4)-iO/i-(d-glucopyranosyluronic acid)-(1→3)-d-galactopyranosyl…/p
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机译：在将大肠杆菌（Escherichia coli）K12的煤泥和荚膜多糖（S53和S53C子菌株）和 E的煤泥多糖甲基化之后，基本上得到了相同的甲醇分解产物。大肠杆菌K12（S61），阴沟空气杆菌N.C.T.C. 5290和鼠伤寒沙门氏菌 SL1543。这些是2-iO-甲基-1-岩藻糖，2，3-di-iO-甲基-1-岩藻糖，2，3-di-的甲基糖苷。 O -甲基-d-葡萄糖醛酸甲酯，2,4,6-tri- O -甲基-d-葡萄糖，2,4,6-tri- < i> O -甲基-d-半乳糖和丙酮酸缩酮，4,6- O -（1'-甲氧基羰基亚乙基）-2,3- O -甲基-d-半乳糖。均被鉴定为来自 E的结晶衍生物。大肠杆菌多糖。缩酮的结构通过质子磁共振和质谱分析，并通过裂解为丙酮酸和2，3-二-i-O-甲基-d-半乳糖证明。因此，所有这些多糖均被视为具有相同的基本结构的变体，其中名称被称为可儿酸。尽管含有相同的糖残基，但是从产气克雷伯氏菌（1.2菌株）的胞外多糖甲基化后获得了截然不同的甲醇分解产物。 E的羟丙基酯。大肠杆菌多糖在无水条件下用碱处理时，在尿酸盐残基上进行β-消除反应，并释放出4,6-O'-（1'-烷氧基羰基亚乙基）-d-半乳糖。连同鉴定作为部分水解产物的3- O -（d-吡喃葡萄糖基尿嘧啶酸）-d-半乳糖，这确定了大多数（如果不是全部）侧链的性质，即 O -[4,6- O -（1'-羧亚乙基）-d-吡喃半乳糖基]-（1→4）- O -（d -吡喃葡萄糖基糖醛酸）-（1→3）-d-吡喃半乳糖基...
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