Study of a novel glycoconjugate, thiopeptidoglycan, and a novel polysaccharide lyase, thiopeptidoglycan lyase
Study of a novel glycoconjugate, thiopeptidoglycan, and a novel polysaccharide lyase, thiopeptidoglycan lyase
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DOI：
10.1016/j.ijbiomac.2010.11.009
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发表时间：
2011-03-01
影响因子：
8.2
通讯作者：
Katahira, Masato
中科院分区：
文献类型：
--
作者：
Kondo, Keiko;Takeda, Minoru;Katahira, Masato
典型的丝状细菌（Sphaerotilus natans）分泌硫醇糖缀合物，该硫醇糖缀合物组装成微管，即所谓的鞘。已知糖复合物由五糖-二肽重复单元组成，但其化学结构尚未完全阐明。为了确定其化学结构，通过过甲酸氧化来分解鞘。释放的磺化衍生物是水溶性的，适合进行详细的核磁共振分析。数据显示存在两个化学计量和一个亚化学计量（相对丰度约为0.5）乙酰化，表明糖复合物由两个等摩尔五糖-二肽重复单元组成，每个重复单元具有两个或三个乙酰基。然而，亚化学计量乙酰化的位置无法确定。为了确定位置，用硫醇选择性荧光试剂对鞘进行衍生化，然后用由鞘降解细菌（Paenibacillus koleovorans）制备的特定多糖裂解酶进行消化。正如预期的那样，通过反相 HPLC 回收了两种荧光消化物，并进行了 NMR 分析。数据显示，两种消化物都是五糖二肽，其还原端和非还原端分别具有不饱和葡萄糖醛酸和半乳糖胺残基。还证实一种消化物具有3-0-乙酰化葡萄糖残基，而另一种具有非衍生化葡萄糖残基。因此，亚化学计量的乙酰化被鉴定为3-O-乙酰化，并且完成了硫醇糖缀合物的结构测定。由于两种消化物结构的澄清，切割位点被指定为与葡萄糖醛酸的 (1 -> 4)-α-半乳糖胺键。基于目前和早期的发现，我们提出了一种名为硫肽聚糖的新型糖复合物类别和一种名为硫肽聚糖裂解酶的新型多糖裂解酶。 (C) 2010 Elsevier B.V. 保留所有权利。
A typical filamentous bacterium, Sphaerotilus natans, secretes a thiolicglycoconjugate which is assembled into a microtube, so called sheath. The glycoconjugate is known to consist of a pentasaccharide-dipeptide repeating unit, but its chemical structure has not been completely elucidated. In order to determine its chemical structure, the sheath was broken down by performic acid oxidation. The released sulfonated derivative was water soluble which was suitable for detailed NMR analysis. The data exhibited the presence of two stoichiometric and one substoichiometric (relative abundance was about 0.5) acetylations, suggesting that the glycoconjugate is composed of two equimolar pentasaccharide-dipeptide repeating units each having either two or three acetyl groups. However, the position of substoichiometric acetylation could not be defined. To determine the position, the sheath was derivatized with a thiol selective fluorescent reagent followed by digestion with a specific polysaccharide lyase prepared from a sheath-degrading bacterium, Paenibacillus koleovorans. As expected, two fluorescent digests were recovered by reverse-phase HPLC and were subjected to NMR analysis. The data revealed that both digests are pentasaccharide-dipeptides which have unsaturated glucuronic acid and galactosamine residues at their reducing and non-reducing ends, respectively. It was also confirmed that one digest has 3-0-acetylated glucose residue while the other has non-derivatized glucose residue. The substoichiometric acetylation was thus identified with the 3-O-acetylation, and structural determination of the thiolic glycoconjugate was completed. By virtue of the clarification of the two digests' structures, the cleavage site was specified as (1 -> 4)-alpha-galactosaminic bond to glucuronic acid. Based on the present and earlier findings, we propose a novel glycoconjugate category named thiopeptidoglycan and a novel polysaccharide lyase named thiopeptidoglycan lyase. (C) 2010 Elsevier B.V. All rights reserved.