hexa-N-acetylchitohexaose

• 分子结构分类: 有机化合物 - 有机氧化合物
• 英文名称: hexa-N-acetylchitohexaose
• 英文别名: chitohexaose；(GlcNAc)6；hexa-N-acetyl chitohexaose；N-[(3R,4R,5S,6R)-5-[(2S,3R,4R,5S,6R)-3-acetamido-5-[(2S,3R,4R,5S,6R)-3-acetamido-5-[(2S,3R,4R,5S,6R)-3-acetamido-5-[(2S,3R,4R,5S,6R)-3-acetamido-5-[(2S,3R,4R,5S,6R)-3-acetamido-4,5-dihydroxy-6-(hydroxymethyl)oxan-2-yl]oxy-4-hydroxy-6-(hydroxymethyl)oxan-2-yl]oxy-4-hydroxy-6-(hydroxymethyl)oxan-2-yl]oxy-4-hydroxy-6-(hydroxymethyl)oxan-2-yl]oxy-4-hydroxy-6-(hydroxymethyl)oxan-2-yl]oxy-2,4-dihydroxy-6-(hydroxymethyl)oxan-3-yl]acetamide
• 化学式: C₄₈H₈₀N₆O₃₁
• 分子量: 1237.18
• InChiKey: GVTXKCFKWGVHBK-SDEUBOORSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  -13.3
• 重原子数：
  85
• 可旋转键数：
  22
• 环数：
  6.0
• sp3杂化的碳原子比例：
  0.88
• 拓扑面积：
  559
• 氢给体数：
  20
• 氢受体数：
  31

反应信息

• 作为反应物：
  描述：

  hexa-N-acetylchitohexaose 在 Streptomyces coelicolor A3(2) β‑N‑acetylhexosaminidase 、 sodium chloride 作用下， 以 aq. phosphate buffer 为溶剂， 生成 D-GlcNAc
  参考文献：
  名称：

  链霉菌A3（2）β- N-乙酰己糖胺酶的结构和活性为GH20家族的催化和抑制提供了进一步的认识。

  摘要：

  β- N-乙酰基己糖胺酶（HEX）是糖苷酶，其催化葡萄糖和半乳糖构型的N-乙酰基-β - d-己糖胺的糖苷键水解。这些酶在人体生理学中很重要，是碳水化合物和糖模拟物生物催化生产的候选者。在这项研究中，与野生型的三维结构和催化受损E302Q HEX变体从土壤细菌天蓝色链霉菌A3（2）（钪（HEX）以无配体形式和在6-乙酰氨基-6-脱氧-castanospermine（6-Ac-Cas）的存在下溶解。E302Q变体也被捕获为中间体，恶唑啉与活性中心结合。晶体学证据突出了loop 3环境中的结构变异，表明该GH20家族成员重要活性位点残基的构象异质性。将酶研究其β- Ñ朝向几丁低聚物和活性-acetylhexosaminidase p NP-乙酰葡糖-和半乳糖构成Ñ-乙酰己糖胺。动力学分析证实了β（1-4）糖苷键连接底物的偏爱，而HPLC谱支持一种糖苷外切酶机制，该酶从底物的非还原端切割糖。Sc

  DOI：

  10.1021/bi401697j
• 作为产物：
  描述：

  在 bovine kidney α-fucosidase 作用下， 反应 24.0h， 生成 hexa-N-acetylchitohexaose
  参考文献：
  名称：

  Fucosylation of chitooligosaccharides by human  1,6-fucosyltransferase requires a nonreducing terminal chitotriose unit as a minimal structure

  摘要：

  FUT8是一种真核生物α1,6-岩藻糖转移酶，它催化从鸟苷酸二磷酸-β-l-岩藻糖向与天冬氨酸连接的寡糖（N-糖）最内层的GlcNAc转移岩藻糖残基。FUT8的催化结构域在结构上类似于细菌α1,6-岩藻糖转移酶NodZ，该酶在合成Nod因子时作用于氨基聚糖。尽管核苷酸糖和N-糖的底物特异性已被确定，但尚不清楚FUT8是否能够对其他糖链（如氨基聚糖）进行岩藻糖化。本研究的目的是探讨FUT8对一般不被认为是哺乳动物底物的氨基聚糖的作用，结果表明FUT8能够以类似于NodZ的方式对这些结构进行岩藻糖化。令人惊讶的是，通过高效液相色谱、质谱和核磁共振对岩藻糖化产物的结构分析表明，FUT8并不利用还原末端的GlcNAc进行岩藻糖转移，而是更偏好于接受体非还原末端的第三个GlcNAc残基。这些发现表明，FUT8催化氨基聚糖的岩藻糖化类似于NodZ，但反应需要非还原末端的氨基三糖结构。FUT8选择岩藻糖化位点的底物识别机制可能与NodZ不同，这可能是由于FUT8固有的结构因子要求所致。

  DOI：

  10.1093/glycob/cwq064

文献信息

• Glycosyl Bunte Salts: A Class of Intermediates for Sugar Chemistry
  作者：Yasuhiro Meguro、Masato Noguchi、Gefei Li、Shin-ichiro Shoda

  DOI：10.1021/acs.orglett.7b03400

  日期：2018.1.5

  thiosulfates have been discovered as a new class of synthetic intermediates in sugar chemistry, named “glycosyl Bunte salts” after 19th-century German chemist, Hans Bunte. The synthesis was achieved by direct condensation of unprotected sugars and sodium thiosulfate using a formamidine-type dehydrating agent in water–acetonitrile mixed solvent. The application of glycosyl Bunte salts is demonstrated with transformation

  S-糖基硫代硫酸盐已被发现是糖化学中的一类新型合成中间体，以19世纪德国化学家汉斯·邦特（Hans Bunte）的名字命名为“糖基邦特盐”。通过在水-乙腈混合溶剂中使用甲am型脱水剂将未保护的糖和硫代硫酸钠直接缩合来完成合成。通过向其他糖基化合物如1-硫糖，糖基二硫化物，1，6-脱水糖和O-糖苷的转化反应证明了糖基邦特盐的应用。
• Efficient chemoenzymatic synthesis of lipo-chitin oligosaccharides as plant growth promoters
  作者：R. Chambon、G. Despras、A. Brossay、B. Vauzeilles、D. Urban、J.-M. Beau、S. Armand、S. Cottaz、S. Fort

  DOI：10.1039/c5gc00623f

  日期：——

  This is an Accepted Manuscript, which has been through the RSC Publishing peer review process and has been accepted for publication. Accepted manuscripts are published online shortly after acceptance. This version of the article will be replaced by the fully edited, formatted and proof read Advance Article as soon as this is available.

  这是已接受的手稿，已通过RSC出版同行评审过程，并已被接受出版。接受的手稿在接受后不久就会在线发布。一旦可用，此版本的文章将被完全编辑，格式化并提供高级阅读的高级文章代替。
• A glycosynthase derived from an inverting GH19 chitinase from the moss <i>Bryum coronatum</i>
  作者：Takayuki Ohnuma、Tatsuya Fukuda、Satoshi Dozen、Yuji Honda、Motomitsu Kitaoka、Tamo Fukamizo

  DOI：10.1042/bj20120036

  日期：2012.6.15

  BcChi-A, a GH19 chitinase from the moss Bryum coronatum, is an endo-acting enzyme that hydrolyses the glycosidic bonds of chitin, (GlcNAc)n [a β-1,4-linked polysaccharide of GlcNAc (N-acetylglucosamine) with a polymerization degree of n], through an inverting mechanism. When the wild-type enzyme was incubated with α-(GlcNAc)2-F [α-(GlcNAc)2 fluoride] in the absence or presence of (GlcNAc)2, (GlcNAc)2 and hydrogen fluoride were found to be produced through the Hehre resynthesis–hydrolysis mechanism. To convert BcChi-A into a glycosynthase, we employed the strategy reported by Honda et al. [(2006) J. Biol. Chem. 281, 1426–1431; (2008) Glycobiology 18, 325–330] of mutating Ser102, which holds a nucleophilic water molecule, and Glu70, which acts as a catalytic base, producing S102A, S102C, S102D, S102G, S102H, S102T, E70G and E70Q. In all of the mutated enzymes, except S102T, hydrolytic activity towards (GlcNAc)6 was not detected under the conditions we used. Among the inactive BcChi-A mutants, S102A, S102C, S102G and E70G were found to successfully synthesize (GlcNAc)4 as a major product from α-(GlcNAc)2-F in the presence of (GlcNAc)2. The S102A mutant showed the greatest glycosynthase activity owing to its enhanced F− releasing activity and its suppressed hydrolytic activity. This is the first report on a glycosynthase that employs amino sugar fluoride as a donor substrate.

  BcChi-A 是一种来自藓苔 Bryum coronatum 的 GH19 几丁质酶，它是一种内作用酶，可通过倒置机制水解几丁质的糖苷键 (GlcNAc)n[聚合度为 n 的 GlcNAc（N-乙酰葡糖胺）β-1,4 链式多糖]。在没有(GlcNAc)2或有(GlcNAc)2存在的情况下，野生型酶与α-(GlcNAc)2-F [α-(GlcNAc)2氟化物]孵育时，发现(GlcNAc)2和氟化氢是通过Hehre再合成-水解机制产生的。为了将 BcChi-A 转化为糖合成酶，我们采用了 Honda 等人报告的策略[（2006）J. Biol. Chem. 281, 1426-1431; （2008）Glycobiology 18, 325-330]，即突变具有亲核水分子的 Ser102 和作为催化碱基的 Glu70，产生 S102A、S102C、S102D、S102G、S102H、S102T、E70G 和 E70Q。在我们使用的条件下，除 S102T 外，所有突变酶都检测不到对 (GlcNAc)6 的水解活性。在无活性的 BcChi-A 突变体中，发现 S102A、S102C、S102G 和 E70G 能在 (GlcNAc)2 存在的情况下成功合成 (GlcNAc)4 作为来自 α-(GlcNAc)2-F的主要产物。S102A 突变体的糖合成酶活性最强，因为它的 F 释放活性增强，水解活性被抑制。这是首次报道使用氨基糖氟化物作为供体底物的糖合成酶。
• Introduction of a tryptophan side chain into subsite +1 enhances transglycosylation activity of a GH-18 chitinase from Arabidopsis thaliana, AtChiC
  作者：N. Umemoto、T. Ohnuma、M. Mizuhara、H. Sato、K. Skriver、T. Fukamizo

  DOI：10.1093/glycob/cws125

  日期：2013.1.1

  A tryptophan side chain was introduced into subsite +1 of family GH-18 (class V) chitinases from Nicotiana tabacum and Arabidopsis thaliana (NtChiV and AtChiC, respectively) by the mutation of a glycine residue to tryptophan (G74W-NtChiV and G75W-AtChiC). The specific activity toward glycol chitin of the two mutant enzymes was 70–71% of that of the wild type. Using chitin oligosaccharides, (GlcNAc)n (n = 4, 5 and 6), as the substrates, we found the transglycosylation reaction to be significantly enhanced in G74W-NtChiV and G75W-AtChiC when compared with the corresponding wild-type enzymes. The introduced tryptophan side chain might protect the oxazolinium ion intermediate from attack by a nucleophilic water molecule. The enhancement of transglycosylation activity was much more distinct in G75W-AtChiC than in G74W-NtChiV. Nuclear magnetic resonance titration experiments using the inactive double mutants, E115Q/G74W-NtChiV and E116Q/G75W-AtChiC revealed that the association constant of (GlcNAc)5 was considerably larger for the latter. Amino acid substitutions at the acceptor binding site might have resulted in the larger association constant for G75W-AtChiC, giving rise to the higher transglycosylation activity of G75W-AtChiC.

  通过将甘氨酸残基突变为色氨酸（G74W-NtChiV 和 G75W-AtChiC），在烟草和拟南芥的 GH-18 家族（V 类）几丁质酶（分别为 NtChiV 和 AtChiC）的子位点 +1 中引入了色氨酸侧链。这两种突变体酶对乙二醇甲壳素的特异性活性是野生型的 70-71%。以甲壳素寡糖（GlcNAc）n（n = 4、5 和 6）为底物，我们发现与相应的野生型酶相比，G74W-NtChiV 和 G75W-AtChiC 的转糖基化反应明显增强。引入的色氨酸侧链可能会保护草唑啉鎓离子中间体免受亲核水分子的攻击。与 G74W-NtChiV 相比，G75W-AtChiC 中转糖基化活性的增强更为明显。使用无活性的双突变体 E115Q/G74W-NtChiV 和 E116Q/G75W-AtChiC 进行的核磁共振滴定实验表明，后者（GlcNAc）5 的结合常数要大得多。受体结合位点的氨基酸取代可能导致 G75W-AtChiC 的结合常数更大，从而使 G75W-AtChiC 的转糖基化活性更高。
• Purification, cDNA cloning, and characterization of LysM-containing plant chitinase from horsetail (<i>Equisetum arvense</i>)
  作者：Saki Inamine、Shoko Onaga、Takayuki Ohnuma、Tamo Fukamizo、Toki Taira

  DOI：10.1080/09168451.2015.1025693

  日期：2015.8.3

  Chitinase-A (EaChiA), molecular mass 36 kDa, was purified from the vegetative stems of a horsetail (Equisetum arvense) using a series of column chromatography. The N-terminal amino acid sequence of EaChiA was similar to the lysin motif (LysM). A cDNA encoding EaChiA was cloned by rapid amplification of cDNA ends and polymerase chain reaction. It consisted of 1320 nucleotides and encoded an open reading frame of 361 amino acid residues. The deduced amino acid sequence indicated that EaChiA is composed of a N-terminal LysM domain and a C-terminal plant class IIIb chitinase catalytic domain, belonging to the glycoside hydrolase family 18, linked by proline-rich regions. EaChiA has strong chitin-binding activity, however, no antifungal activity. This is the first report of a chitinase from Equisetopsida, a class of fern plants, and the second report of a LysM-containing chitinase from a plant.

  摘要：从一种铁线莲（Equisetum arvense）的营养茎中纯化出分子量为36 kDa的壳聚糖酶A（EaChiA），使用一系列柱层析技术。EaChiA的N末端氨基酸序列与赖氨酸基序（LysM）相似。通过快速扩增cDNA末端和聚合酶链反应克隆了编码EaChiA的cDNA。它由1320个核苷酸组成，编码一个361个氨基酸残基的开放阅读框。推测的氨基酸序列表明，EaChiA由一个N末端LysM结构域和一个C末端植物IIIb类壳聚糖酶催化结构域组成，属于18号糖苷水解酶家族，通过富含脯氨酸的区域连接。EaChiA具有强壳聚糖结合活性，但没有抗真菌活性。这是首次报道了来自蕨类植物Equisetopsida的壳聚糖酶，也是来自植物的第二份含有LysM的壳聚糖酶的报道。