NMR study of the galactomannans of Trichophyton mentagrophytes and Trichophyton rubrum
NMR study of the galactomannans of Trichophyton mentagrophytes and Trichophyton rubrum
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DOI：
10.1042/bj3230297
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发表时间：
1997-04-01
影响因子：
4.1
通讯作者：
Okawa, Y
中科院分区：
文献类型：
--
作者：
Ikuta, K;Shibata, N;Okawa, Y
大约 90% 的慢性皮肤癣菌感染是由须癣毛癣菌和红色毛癣菌引起的。慢性感染的原因之一在于这些生物体细胞壁成分的免疫抑制作用。因此，我们试图鉴定半乳甘露聚糖（主要细胞壁成分之一）的化学结构。从培养基中分离须毛癣菌和红色毛癣菌分泌的细胞壁多糖，并通过 DEAE-Sephadex 色谱法将其分成三个亚级分。通过NMR对每个亚级分的分析表明存在两种多糖，即甘露聚糖和半乳甘露聚糖。甘露聚糖具有由α1,6-连接的甘露糖单元组成的线性主链，以及作为侧链的α1,2-连接的甘露糖单元。通过酸处理除去呋喃半乳糖单元后，通过连续 NMR 归属方法分析半乳甘露聚糖的核心甘露聚糖部分。结果表明，甘露聚糖部分具有由α1,6键连接的α1,2-连接的甘露四糖单元的线性重复结构。由于 α 1,6 连接甘露糖单元的空间效应，四糖单元的两个中间 α 1,2 连接甘露糖的 H-1 信号显示出显着的上场偏移（Delta delta = 0.05-0.08 p.p,m.）。通过与酸修饰产物的信号相比，半乳甘露聚糖的低场移动的 C-13 信号的分配，确定呋喃半乳糖单元在核心甘露聚糖的 C-3 处的附着点。在这些半乳甘露聚糖中，不存在在查尔斯青霉和烟曲霉中发现的聚呋喃半乳糖基链。
Around 90% of chronic dermatophyte infections are caused by the fungi Trichophyton mentagrophytes and Trichophyton rubrum. One of the causes of the chronic infection resides in the immunosuppressive effects of the cell-wall components of these organisms. Therefore we have attempted to identify the chemical structure of galactomannan, one of the major cell-wall components. The cell-wall polysaccharides secreted by T. mentagrophytes and T. rubrum were isolated from the culture medium and fractionated into three subfractions by DEAE-Sephadex chromatography. Analysis of each subfraction by NMR indicated that there are two kinds of polysaccharides present, i.e. mannan and galactomannan. The mannan has a linear backbone consisting of alpha 1,6-linked mannose units, with alpha 1,2-linked mannose units as side chains. The core mannan moiety of the galactomannan was analysed by a sequential NMR assignment method after removing the galactofuranose units by acid treatment. The result indicates that the mannan moiety has a linear repeating structure of alpha 1,2-linked mannotetraose units connected by an alpha 1,6 linkage. The H-1 signals of the two intermediary alpha 1,2-linked mannoses of the tetraose unit showed a significant upfield shift (Delta delta = 0.05-0.08 p.p,m.), due to the steric effect of an alpha 1,6-linked mannose unit. The attachment point of the galactofuranose units was determined at C-3 of the core mannan by the assignment of the downfield-shifted C-13 signals of the galactomannan compared with those of the acid-modified product. In these galactomannans there were no polygalactofuranosyl chains which have been found in Penicillium charlesii and Aspergillus fumigatus.