辅酶Q8 | 2394-68-5

• 分子结构分类: 有机化合物 - 脂质和类脂质分子 - 异戊烯醇脂质
• 中文名称: 辅酶Q8
• 英文名称: ubiquinone 8
• 英文别名: Coenzyme Q8；2,3-dimethoxy-5-methyl-6-[(2E,6E,10E,14E,18E,22E,26E)-3,7,11,15,19,23,27,31-octamethyldotriaconta-2,6,10,14,18,22,26,30-octaenyl]cyclohexa-2,5-diene-1,4-dione
• CAS: 2394-68-5
• 化学式: C₄₉H₇₄O₄
• 分子量: 727.124
• InChiKey: ICFIZJQGJAJRSU-SGHXUWJISA-N

物化性质

• 熔点：
  36.6-37 °C
• 沸点：
  782.9±60.0 °C(Predicted)
• 密度：
  0.97±0.1 g/cm3(Predicted)

计算性质

• 辛醇/水分配系数(LogP)：
  15.7
• 重原子数：
  53
• 可旋转键数：
  25
• 环数：
  1.0
• sp3杂化的碳原子比例：
  0.55
• 拓扑面积：
  52.6
• 氢给体数：
  0
• 氢受体数：
  4

反应信息

• 作为反应物：
  描述：

  辅酶Q8 在 sodium tetrahydroborate 作用下， 以 甲醇 、 正己烷 为溶剂， 反应 0.08h， 生成 ubiquinol-8
  参考文献：
  名称：

  A genome-wide screen in Escherichia coli reveals that ubiquinone is a key antioxidant for metabolism of long-chain fatty acids

  摘要：

  Long-chain fatty acids (LCFAs) are used as a rich source of metabolic energy by several bacteria including important pathogens. Because LCFAs also induce oxidative stress, which may be detrimental to bacterial growth, it is imperative to understand the strategies employed by bacteria to counteract such stresses. Here, we performed a genetic screen in Escherichia coli on the LCFA, oleate, and compared our results with published genome-wide screens of multiple non-fermentable carbon sources. This large-scale analysis revealed that among components of the aerobic electron transport chain (ETC), only genes involved in the biosynthesis of ubiquinone, an electron carrier in the ETC, are highly required for growth in LCFAs when compared with other carbon sources. Using genetic and biochemical approaches, we show that this increased requirement of ubiquinone is to mitigate elevated levels of reactive oxygen species generated by LCFA degradation. Intriguingly, we find that unlike other ETC components whose requirement for growth is inversely correlated with the energy yield of non-fermentable carbon sources, the requirement of ubiquinone correlates with oxidative stress. Our results therefore suggest that a mechanism in addition to the known electron carrier function of ubiquinone is required to explain its antioxidant role in LCFA metabolism. Importantly, among the various oxidative stress combat players in E. coli, ubiquinone acts as the cell's first line of defense against LCFA-induced oxidative stress. Taken together, our results emphasize that ubiquinone is a key antioxidant during LCFA metabolism and therefore provides a rationale for investigating its role in LCFA-utilizing pathogenic bacteria.

  DOI：

  10.1074/jbc.m117.806240
• 作为产物：
  描述：

  反式-3-羟甲基-2-丁烯基氯 在 sodium tetrahydroborate 、 N-氯代丁二酰亚胺 、 正丁基锂 、 二氯二茂锆 、 [1,3-双(二苯基膦基)丙烷]二氯化钯(II) 、 二甲基硫 、 磷酸 、 四丁基氟化铵 、 三乙基硼氢化锂 、 二甲基亚砜 、 N,N'-二环己基碳二亚胺 作用下， 以 四氢呋喃 、 正己烷 、 二氯甲烷 、 1,2-二氯乙烷 、 苯 为溶剂， 反应 144.0h， 生成 辅酶Q8
  参考文献：
  名称：

  A Convergent Approach to Coenzyme Q

  摘要：

  Syntheses of coenzyme Q(3-8) are described, as well as related systems such as plastoquinone-5. Preparation of thr higher homologues of the ubiquinones relies on two new conjunctive reagents, or "linchpins", each of which ultimately corresponds to two or three prenyl units. These allow for attachment of a polyprenyl halide at one end, followed by a Ni(0)-catalyzed cross-coupling at the other terminus with a chloromethylated p-quinone.

  DOI：

  10.1021/ja992164p

文献信息

• Structural and Biochemical Evidence for an Enzymatic Quinone Redox Cycle in Escherichia coli
  作者：Melanie A. Adams、Zongchao Jia

  DOI：10.1074/jbc.m412637200

  日期：2005.3

  enzymatic reaction. We therefore refer to YgiN as quinol monooxygenase. Modulator of drug activity B is reported to be involved in the protection of cells from reactive oxygen species formed during single electron oxidation and reduction reactions. The enzymatic activities, together with the structural characterization of YgiN, lend evidence to the possible existence of a novel quinone redox cycle in E

  天然合成的醌具有多种重要的细胞功能。大肠杆菌同时产生泛醌和甲萘醌，它们参与电子传递。但是，在这些化合物的单电子还原过程中以及通过羟基醌产物的自氧化产生的半醌中间体会产生活性氧，从而对细胞产生压力。在这里，我们介绍了迄今未知功能的蛋白质YgiN的晶体结构。YgiN的三维折叠类似于ActVA-Orf6单加氧酶，后者作用于羟基醌底物。YgiN与“药物活性B的调节剂”共享一个启动子，该蛋白的活性类似于能够还原二甲酮的哺乳动物DT-黄递酶的活性。YgiN能够重新氧化薄荷脑，
• Functions of the Membrane-Associated and Cytoplasmic Malate Dehydrogenases in the Citric Acid Cycle of <i>Escherichia coli</i>
  作者：Michel E. van der Rest、Christian Frank、Douwe Molenaar

  DOI：10.1128/jb.182.24.6892-6899.2000

  日期：2000.12.15

  mqo expression. On the contrary, MQO and MDH are active at the same time in E. coli. For Corynebacterium glutamicum, it was found that MQO is the principal enzyme catalyzing the oxidation of malate to oxaloacetate. These observations justified a reinvestigation of the roles of MDH and MQO in the citric acid cycle of E. coli. In this organism, a defined deletion of the mdh gene led to severely decreased

  大肠杆菌中苹果酸氧化为草酰乙酸可以通过两种酶催化：众所周知的NAD依赖性苹果酸脱氢酶（MDH; EC 1.1.1.37）和膜相关的苹果酸：醌-氧化还原酶（MQO; EC 1.1.99.16） ，由基因mqo（以前称为yojH）编码。mqo基因的表达以及因此的MQO活性受碳和生长能源的调节。在分批培养中，MQO活性在指数生长期间最高，而在固定相开始后急剧下降。将β-半乳糖苷酶报告基因与mqo基因启动子融合的实验表明，其转录受ArcA-ArcB两组分系统调控。与早期报道相反，MDH不能抑制mqo表达。相反，MQO和MDH在大肠杆菌中同时具有活性。对于谷氨酸棒杆菌，发现MQO是催化苹果酸氧化为草酰乙酸的主要酶。这些观察结果证明对MDH和MQO在大肠杆菌柠檬酸循环中的作用进行了重新研究。在这种生物中，mdh基因的明确缺失导致在几种底物上的生长速率大大降低。mqo基因的缺失不会对生长速率产生明显的影
• NapGH components of the periplasmic nitrate reductase of Escherichia coli K-12: location, topology and physiological roles in quinol oxidation and redox balancing
  作者：T. Harma C. BRONDIJK、Arjaree NILAVONGSE、Nina FILENKO、David J. RICHARDSON、Jeffrey A. COLE

  DOI：10.1042/bj20031115

  日期：2004.4.1

  Nap (periplasmic nitrate reductase) operons of many bacteria include four common, essential components, napD, napA, napB and napC (or a homologue of napC). In Escherichia coli there are three additional genes, napF, napG and napH, none of which are essential for Nap activity. We now show that deletion of either napG or napH almost abolished Nap-dependent nitrate reduction by strains defective in naphthoquinone synthesis. The residual rate of nitrate reduction (approx. 1% of that of napG+H+ strains) is sufficient to replace fumarate reduction in a redox-balancing role during growth by glucose fermentation. Western blotting combined with β-galactosidase and alkaline phosphatase fusion experiments established that NapH is an integral membrane protein with four transmembrane helices. Both the N- and C-termini as well as the two non-haem iron–sulphur centres are located in the cytoplasm. An N-terminal twin arginine motif was shown to be essential for NapG function, consistent with the expectation that NapG is secreted into the periplasm by the twin arginine translocation pathway. A bacterial two-hybrid system was used to show that NapH interacts, presumably on the cytoplasmic side of, or within, the membrane, with NapC. As expected for a periplasmic protein, no NapG interactions with NapC or NapH were detected in the cytoplasm. An in vitro quinol dehydrogenase assay was developed to show that both NapG and NapH are essential for rapid electron transfer from menadiol to the terminal NapAB complex. These new in vivo and in vitro results establish that NapG and NapH form a quinol dehydrogenase that couples electron transfer from the high midpoint redox potential ubiquinone–ubiquinol couple via NapC and NapB to NapA.

  许多细菌的 Nap（周质硝酸还原酶）操作子包括四个常见的基本组成部分：napD、napA、napB 和 napC（或 napC 的同源物）。在大肠杆菌中，还有三个基因：napF、napG 和 napH，但它们都不是 Nap 活性所必需的。我们现在的研究表明，在萘醌合成缺陷菌株中，napG 或 napH 的缺失几乎消除了 Nap 依赖性硝酸盐还原。残余的硝酸盐还原率（约为 napG+H+ 菌株的 1%）足以取代富马酸还原，在葡萄糖发酵的生长过程中发挥氧化还原平衡作用。Western 印迹法结合 β-半乳糖苷酶和碱性磷酸酶融合实验证实，NapH 是一种具有四个跨膜螺旋的整体膜蛋白。N 端和 C 端以及两个非血红素铁硫中心都位于细胞质中。研究表明，N末端的精氨酸孪生基团对NapG的功能至关重要，这与NapG通过精氨酸孪生基团转运途径分泌到外质的预期一致。细菌双杂交系统显示，NapH 可能在细胞质一侧或膜内与 NapC 相互作用。正如预期的那样，在细胞质中，NapG 与 NapC 或 NapH 没有相互作用。一种体外喹啉脱氢酶试验表明，NapG 和 NapH 对于从红豆杉醇到终端 NapAB 复合物的快速电子传递都是必不可少的。这些新的体内和体外研究结果证实，NapG 和 NapH 形成了一种醌脱氢酶，将高中点氧化还原电位的泛醌-泛醌醇偶联物的电子转移通过 NapC 和 NapB 传导到 NapA。
• Regio- and stereoselective synthesis of coenzymes Qn (n = 2-10), vitamin K, and related polyprenylquinones
  作者：Yoshinori Naruta

  DOI：10.1021/jo01309a006

  日期：1980.10
• Terao,S. et al., Journal of the Chemical Society. Perkin transactions I, 1978, p. 1101 - 1110
  作者：Terao,S. et al.

  DOI：——

  日期：——