BACKGROUND & AIMS: :Ubiquinol (QH), a reduced form of coenzyme Q10, is a lipid antioxidant that is hydro-soluble and is commonly formulated in commercial supplements. Ubiquinol has been increasingly reported to exert antioxidant functions, in addition to its role in the cell energy-producing system of mitochondria and adenosine triphosphate (ATP) production. The aim of this study was to assess the potential beneficial effects of QH on anti-fatigue and ergogenic functions following physiological challenge. Forty 8-week-old male Institute of Cancer Research (ICR) mice were divided into four groups (n = 10 for each group): Group 1 (vehicle control or oil only); Group 2 (1X QH dose or 102.5 mg/kg); Group 3 (2X QH dose or 205 mg/kg); Group 4 (6X QH dose or 615 mg/kg). Anti-fatigue activity and exercise performance were studied using the forelimb grip strength experiment and exhaustive weight-loaded swimming time, and levels of serum lactate, ammonia, glucose, BUN (blood urea nitrogen), creatine kinase (CK), and free fatty acids (FFA) after an acute exercise challenge. The forelimb grip strength and exhaustive weight-loaded swimming time of the QH-6X group were significantly higher than those of the other groups. QH supplementation dose-dependently reduced serum lactate, ammonia, and CK levels and increased the FFA concentration after acute exercise. In addition, QH increased the liver and muscle glycogen content, an important energy source during exercise. Therefore, the results suggest that QH formulation is a safe dietary supplement for amelioration of fatigue and for promoting exercise performance.

背景与目标： : 泛醇 (QH) 是辅酶Q10的一种还原形式，是一种水溶性的脂质抗氧化剂，通常在商业补充剂中配制。除了在线粒体和三磷酸腺苷 (ATP) 产生的细胞能量产生系统中的作用外，泛醇已被越来越多地报道具有抗氧化功能。这项研究的目的是评估QH对生理挑战后抗乏力和人体功能的潜在有益作用。将40只8周龄的雄性癌症研究所 (ICR) 小鼠分为四组 (每组n = 10): 第1组 (仅载具对照或油); 第2组 (1X QH剂量或102.5 mg/kg); 第3组 (2X QH剂量或205 mg/kg); 第4组 (6xqh剂量或615 mg/kg)。通过前肢握力实验和力竭负重游泳时间，以及血清乳酸，氨，葡萄糖，BUN (血尿素氮)，肌酸激酶 (CK) 和游离脂肪酸 (FFA) 的水平，研究了抗乏力活动和运动性能。急性运动挑战后。QH-6X组的前肢握力和力竭负重游泳时间明显高于其他组。补充QH剂量依赖性地降低急性运动后的血清乳酸，氨和CK水平，并增加FFA浓度。此外，QH增加了肝脏和肌肉糖原含量，这是运动过程中的重要能量来源。因此，结果表明QH制剂是一种安全的膳食补充剂，可改善乏力并促进运动表现。

BACKGROUND & AIMS: The bo-type ubiquinol oxidase of Escherichia coli is a member of the superfamily of heme-copper oxidases which also includes the aa3-type cytochrome c oxidases. The oxygen-binding binuclear center of cytochrome bo is located in subunit I and consists of a heme (heme o; heme a3 in the aa3-type oxidases) and a copper (Cu(B)). Previous spectroscopic studies have shown that heme o is bound to the protein via a single histidine residue. Site-directed mutagenesis of conserved histidine residues in subunit I has identified two residues (H284 and H419) which are candidates for the ligand of heme o, while spectroscopic studies of mutants at H284 definitively demonstrated that this residue cannot be the axial ligand. Consequently, the single remaining conserved histidine in subunit I (H419) was assigned as the ligand for the heme of the binuclear center. In this paper, this assignment is tested by characterization of additional mutants in which the putative heme o axial ligand, H419, is replaced by other amino acids. All mutations at H419 result in the loss of enzyme activity. Analyses via UV-visible and Fourier transform infrared spectroscopies reveal that substantial perturbation has occurred at the binuclear center as a result of the amino acid substitutions. In contrast with the wild-type enzyme, the mutant enzymes bind very little carbon monoxide. Three other amino acid residues which are potential ligands for heme o are shown tob e nonessential for enzyme activity. Mutations in these residues do not perturb the UV-visible or FTIR spectroscopic characteristics of the enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)

背景与目标： 大肠杆菌的bo型泛醇氧化酶是血红素-铜氧化酶超家族的成员，该超家族还包括aa3-type的细胞色素c氧化酶。细胞色素bo的氧结合双核中心位于亚基I中，由血红素 (血红素o; aa3-type氧化酶中的血红素a3) 和铜 (Cu(B)) 组成。先前的光谱研究表明，血红素o通过单个组氨酸残基与蛋白质结合。亚基I中保守的组氨酸残基的定点诱变已经确定了两个残基 (H284和H419)，它们是血红素o配体的候选物，而H284突变体的光谱研究明确表明该残基不能是轴向配体。因此，将亚基I (H419) 中剩余的单个保守组氨酸指定为双核中心血红素的配体。在本文中，通过表征其他突变体来测试此分配，其中推定的血红素o轴向配体H419被其他氨基酸取代。H419的所有突变都会导致酶活性的丧失。通过紫外可见和傅立叶变换红外光谱进行的分析表明，由于氨基酸取代，双核中心发生了很大的扰动。与野生型酶相反，突变酶结合的一氧化碳很少。显示出其他三个作为血红素o潜在配体的氨基酸残基对酶活性不重要。这些残基中的突变不会干扰酶的紫外可见或FTIR光谱特征。(摘要截短于250字)

BACKGROUND & AIMS: :Previous flow-flash measurements using the bo-type ubiquinol oxidase of Escherichia coli have revealed that facilitated heme B-heme O intramolecular electron transfer initiated upon reaction of the fully-reduced enzyme with dioxygen proceeds with a rate constant higher than 5 x 10(4) s-1 at pH 7.4 and 20 degrees C. Depletion of chloride anions from the enzyme by HPLC performed in the present study considerably decreased the rate constant to approximately 700 s-1, but the reaction of either dioxygen or carbon monoxide at the binuclear center was not affected at all kinetically. These results strongly suggest that Cl- is essential in maintaining a subtle molecular structure around the heme B and heme O that enables facilitated intramolecular electron transfer. Furthermore, a series of absorption spectra of the enzyme collected on time scales from microseconds to milliseconds during its single turnover indicate that as heme-heme intramolecular electron transfer is retarded by depletion of Cl-, an alternative electron transfer pathway is invoked. We discuss a possible role of novel bound Cl- in electron transfer from bound quinol to the binuclear center to accomplish dioxygen reduction.

背景与目标： : 先前使用大肠杆菌的bo型泛醇氧化酶的流动闪蒸测量已经揭示，促进血红素B-血红素O分子内电子转移在完全还原的酶与二氧反应后开始，以高于5 × 10(4) 的速率常数s-1在pH 7.4和20 ℃ 下进行。在本研究中进行的通过HPLC从酶中消耗氯离子相当大地降低了速率常数至大约700 s-1，但是双核中心处的双氧或一氧化碳的反应在动力学上完全没有受到影响。这些结果强烈表明，Cl-对于维持血红素B和血红素O周围的微妙分子结构至关重要，从而促进了分子内电子转移。此外，在单次周转期间以微秒到毫秒的时间尺度收集的酶的一系列吸收光谱表明，由于血红素-血红素分子内电子转移因Cl-的耗尽而受阻，因此会调用另一种电子转移途径。我们讨论了新型结合Cl-在从结合的喹啉到双核中心的电子转移中以实现双氧还原的可能作用。

BACKGROUND & AIMS: :Rhodobacter capsulatus utilizes two terminal oxidases for aerobic respiration, cytochrome cbb(3) and ubiquinol oxidase. To determine the transcription factors involved in terminal oxidase expression, ccoN-lacZ and cydA-lacZ protein fusions were assayed in a variety of regulatory mutants. The results of this and previous studies indicate that cytochrome cbb(3) expression is controlled by regB-regA, fnrL, and hvrA and that ubiquinol oxidase expression is controlled by regB-regA, fnrL, hvrA, crtJ, and aerR.

背景与目标： : 荚膜红杆菌利用两种末端氧化酶进行有氧呼吸，细胞色素cbb(3) 和泛醇氧化酶。为了确定与末端氧化酶表达有关的转录因子，在多种调节突变体中测定了ccoN-lacZ和cydA-lacZ蛋白融合。这项研究和以前的研究结果表明，细胞色素cbb(3) 的表达受regB-regA，fnrL和hvrA控制，而泛醇氧化酶的表达受regB-regA，fnrL，hvrA，crtJ和aerR控制。

BACKGROUND & AIMS: :Endogenous ubiquinones (UQ) such as coenzyme Q(10) are essential electron carriers in the mitochondrial respiratory chain, and the reduced ubiquinol form (UQH(2)) is a chain-breaking antioxidant, decreasing oxidative damage caused by lipid peroxidation within mitochondria. Consequently, exogenous UQ are used as therapies to decrease mitochondrial oxidative damage. The proximal radical produced during mitochondrial oxidative stress is superoxide (O(2)(.-)) and the reaction between UQ and O(2)(.-) to form the ubisemiquinone radical anion (UQ(.-)) may also be important for the scavenging of O(2)(.-) by exogenous UQ. The situation in vivo is that many UQ are predominantly located in the hydrophobic membrane core, from which O(2)(.-) will be excluded but its conjugate acid, HOO(.), can enter. The reactivity of UQ or UQH(2) with HOO(.) has not been reported previously. Here a pulse radiolysis study on the reactions between UQ/UQH(2) and O(2)(.-)/HOO(.) in water and in solvent systems mimicking the surface and core of biological membranes has been undertaken. O(2)(.-) reacts very rapidly with UQ, suggesting that this may contribute to the scavenging of O(2)(.-) in vivo. In contrast, UQH(2) reacts relatively slowly with HOO(.), but rapidly with other oxygen- and carbon-centered radicals, indicating that the antioxidant role of UQH(2) is mainly in preventing lipid peroxidation.

背景与目标： : 内源性泛醌 (UQ) (例如辅酶q (10)) 是线粒体呼吸链中必不可少的电子载体，而还原的泛醌形式 (UQH(2)) 是一种破坏链的抗氧化剂，可减少脂质过氧化引起的氧化损伤线粒体内。因此，外源性UQ被用作减少线粒体氧化损伤的疗法。线粒体氧化应激过程中产生的近端自由基是超氧化物 (O(2)(.-))，UQ与O(2)(.-) 之间的反应形成乌比二苯醌自由基阴离子 (UQ(.-)) 也可能对清除O(2)(.-) 通过外源UQ。体内的情况是，许多UQ主要位于疏水性膜核中，其中O(2)(.-) 将被排除，但其共轭酸HOO(.) 可以进入。UQ或UQH(2) 与HOO(.) 的反应性以前没有报道过。在这里，对UQ/UQH(2) 和O(2)/HOO(.-)/HOO(.) 在水和模拟生物膜表面和核心的溶剂系统中的反应进行了脉冲辐射分解研究。O(2)(.-) 与UQ反应非常迅速，表明这可能有助于体内清除O(2)(.-)。相反，UQH(2) 与HOO(.) 反应相对较慢，但与其他以氧和碳为中心的自由基反应迅速，表明UQH(2) 的抗氧化作用主要是防止脂质过氧化。

BACKGROUND & AIMS: :Biochemical analyses of Rubrivivax gelatinosus membranes have revealed that the cytochrome bc(1) complex is highly resistant to classical inhibitors including myxothiazol, stigmatellin, and antimycin. This is the first report of a strain exhibiting resistance to inhibitors of both catalytic Q(0) and Q(i) sites. Because the resistance to cytochrome bc(1) inhibitors is primarily related to the cytochrome b primary structure, the petABC operon encoding the subunits of the cytochrome bc(1) complex of Rubrivivax gelatinosus was sequenced. In addition to homologies to the corresponding proteins from other organisms, the deduced amino acid sequence of the cytochrome b polypeptide shows (i) an E303V substitution in the highly conserved PEWY loop involved in quinol/stigmatellin binding, (ii) other substitutions that could be involved in resistance to cytochrome bc(1) inhibitors, and (iii) 14 residues instead of 13 between the histidines in helix IV that likely serve as the second axial ligand to the b(H) and b(L) hemes, respectively. These characteristics imply different functional properties of the cytochrome bc(1) complex of this bacterium. The consequences of these structural features for the resistance to inhibitors and for the properties of R. gelatinosus cytochrome bc(1) are discussed with reference to the structure and function of the cytochrome bc(1) complexes from other organisms.

背景与目标： : 红斑明胶膜的生化分析表明，细胞色素bc(1) 复合物对包括粘噻唑，柱状霉素和抗霉素在内的经典抑制剂具有高度抗性。这是对催化Q(0) 和Q(i) 位点的抑制剂表现出抗性的菌株的首次报道。由于对细胞色素bc(1) 抑制剂的抗性主要与细胞色素b一级结构有关，因此对编码红斑明胶的细胞色素bc(1) 复合物亚基的petABC操纵子进行了测序。除了与来自其他生物体的相应蛋白质的同源性外，推导的细胞色素b多肽的氨基酸序列还显示 (i) 在高度保守的PEWY环中涉及喹啉/柱状蛋白结合的E303V取代，(ii) 可能与对细胞色素bc(1) 抑制剂的抗性有关的其他取代，以及 (iii) 螺旋IV中的组氨酸之间的14个残基而不是13个残基，它们可能分别充当b(H) 和b(L) 血红素的第二个轴向配体。这些特征暗示了该细菌的细胞色素bc(1) 复合物的不同功能特性。参考其他生物的细胞色素bc(1) 复合物的结构和功能，讨论了这些结构特征对抑制剂的抗性和明胶R. gelatinosus细胞色素bc(1) 的性质的后果。

BACKGROUND & AIMS: :Ubiquinol-cytochrome c reductase hinge protein (UQCRH), as a connecter between cytochrome c1 with cytochrome c in complex III of respiratory chain, is top-ranked hypermethylated gene in clear cell renal cell carcinoma (ccRCC). This study aims to evaluate the impact of UQCRH on recurrence and survival of 424 ccRCC patients enrolled retrospectively from a single institution after surgical resection using immunohistochemistry method. UQCRH was specifically downregulated in ccRCC, compared with papillary and chromophobe RCC. Moreover, patients with low UQCRH were prone to possess high T stage and TNM stage and associated with poor survival and early recurrence. UQCRH remained an independent favorable prognosticator for OS (Hazard rate [HR]: 0.510, 95% CI: 0.328-0.795, p=0.003) and RFS (HR: 0.506, 95% CI: 0.334-0.767, p=0.001) adjusting with other well-established factors using backward Cox model. Furthermore, in stratified subgroups, patients with low UQCRH had an increased risk of recurrence (HR: 0.452, 95% CI: 0.261-0.783, p=0.005) and mortality (HR: 0.386, 95% CI: 0.205-0.726, p=0.003) in subgroup of early TNM stage. Taken together, UQCRH is a potential independent favorable prognostic factor for recurrence and survival of patients with ccRCC after nephrectomy.

背景与目标： : 泛醇-细胞色素c还原酶铰链蛋白 (UQCRH) 是细胞色素c1与呼吸链复合体III中的细胞色素c之间的连接物，是透明细胞肾细胞癌 (ccRCC) 中排名最高的高甲基化基因。本研究旨在通过免疫组织化学方法评估UQCRH对424例ccRCC患者术后复发和生存的影响。与乳头状和嫌色RCC相比，UQCRH在ccRCC中特异性下调。此外，低UQCRH患者容易具有高T期和TNM期，并伴有较差的生存率和早期复发。UQCRH仍然是OS (危险率 [HR]: 0.510，95% CI: 0.328-0.795，p = 0.003) 和RFS (HR: 0.506，95% CI: 0.334-0.767，p = 0.001) 的独立有利的预测指标。使用向后Cox模型与其他已建立的因素进行调整。此外，在分层亚组中，低UQCRH的患者在TNM早期亚组中复发风险 (HR: 0.452，95% CI: 0.261-0.783，p = 0.005) 和死亡率 (HR: 0.386，95% CI: 0.205-0.726，p = 0.003) 增加。综合来看，UQCRH是ccRCC患者肾切除术后复发和生存的潜在独立有利预后因素。

BACKGROUND & AIMS: The present paper describes the sensitivity of the mitochondrial nicotinamide nucleotide transhydrogenase (EC 1.6.1.1) to oxidative modification, and the effects of endogenous ubiquinol on this modification. A comparison is made between the effects of treatment with ADP-Fe3+ and ascorbate and with peroxynitrite, using kinetic, electrophoretic, and immunological analyses, together with lipid peroxidation measurements. The transhydrogenase was inactivated by both types of oxidative modification, but apparently through different mechanisms. Ubiquinol protected the enzyme against inactivation only when the modification was caused by ADP-Fe3+ and ascorbate treatment. Kinetic measurements revealed a threefold increase of the Km value of the enzyme for NADPH after exposure to ADP-Fe3+ and ascorbate, and a twofold increase of the Km values for both NADH and NADPH after exposure to peroxynitrite. NAD(H) exerted a protection against trans-hydrogenase inactivation when added to the preincubation in the case of peroxynitrite, but neither NAD(H) or NADP(H) protected in the case of ADP-Fe3+ and ascorbate. Using immunoblotting it was shown that the enzyme became both aggregated and fragmented, although to different extents, depending on the oxidative system used. Again, ubiquinol prevented these effects only in the case of ADP-Fe3+ and ascorbate treatment. Furthermore, there occurred a striking decrease in the 66-kDa trypsin fragment after exposure of the enzyme to ADP-Fe3+ and ascorbate, and of the 48-kDa trypsin fragment after exposure to peroxynitrite. It is concluded that the mitochondrial nicotinamide nucleotide transhydrogenase is sensitive to oxidative stress and that the mechanism underlying this can vary according to the challenge to which the enzyme is exposed. Endogenous ubiquinol may play a role in protecting the enzyme against agents perturbing the lipid phase of the membrane.

背景与目标： 本文描述了线粒体烟酰胺核苷酸转酸酶 (EC 1.6.1.1) 对氧化修饰的敏感性，以及内源性泛醇对这种修饰的影响。使用动力学，电泳和免疫学分析以及脂质过氧化测量，比较了ADP-Fe3和抗坏血酸盐和过氧亚硝酸盐的治疗效果。两种类型的氧化修饰都使转酸酶失活，但显然是通过不同的机制。泛醇仅当修饰是由ADP-Fe3 + 和抗坏血酸处理引起时才保护酶免于失活。动力学测量显示，暴露于ADP-Fe3和抗坏血酸盐后，NADPH的酶Km值增加了三倍，而暴露于过氧亚硝酸盐后，NADH和NADPH的Km值均增加了两倍。在过氧亚硝酸盐的情况下，将NAD(H) 添加到预孵育中时对反式氢化酶失活具有保护作用，但在ADP-Fe3和抗坏血酸盐的情况下，NAD(H) 或NADP(H) 均未受到保护。使用免疫印迹显示，该酶既聚集又破碎，尽管程度不同，具体取决于所使用的氧化系统。同样，泛醇仅在ADP-Fe3 + 和抗坏血酸处理的情况下阻止了这些作用。此外，酶暴露于ADP-Fe3和抗坏血酸酯后，66 kDa胰蛋白酶片段显着减少，而48 kDa胰蛋白酶片段暴露于过氧亚硝酸盐后显着减少。结论是，线粒体烟酰胺核苷酸转酸酶对氧化应激敏感，其潜在机制可能会根据酶所面临的挑战而变化。内源性泛醇可能在保护酶免受干扰膜脂质相的作用中发挥作用。

BACKGROUND & AIMS: :A preparation containing the Mr 13,400 protein (subunit VI), phospholipid, and ubiquinone was isolated from bovine heart mitochondrial ubiquinol-cytochrome c reductase by a procedure involving Triton X-100 and urea solubilization, calcium phosphate-cellulose column chromatography at different pHs, acetone precipitation, and decanoyl-N-methylglucamide-sodium cholate extraction. The protein in this preparation corresponds to subunit VI of ubiquinol-cytochrome c reductase resolved in the sodium dodecyl sulfate-polyacrylamidce gel electrophoresis system of Schägger et al. (1987, FEBS Lett. 21, 161-168) and has the same amino acid sequence as that of the Mr 13,400 protein reported by Wakabayashi et al. (1985, J. Biol. Chem. 260, 337-343). The phospholipid and ubiquinone present in the preparation copurify with but are not intrinsic components of, the Mr 13,400 protein. This preparation has a potency and behavior identical to that of a free phospholipid preparation in restoring activity to delipidated ubiquinol-cytochrome c reductase. Antibodies against Mr 13,400 react only with Mr 13,400 protein and complexes which contain it. They do not inhibit intact, lipid-sufficient ubiquinol-cytochrome c reductase. However, when delipidated ubiquinol-cytochrome c reductase is incubated with antibodies prior to reconstitution with phospholipid, a 55% decrease in the restoration activity is observed, indicating that the catalytic site-related epitopes of the Mr 13,400 protein are buried in the phospholipid environment. Antibodies against Mr 13,400 cause an increase of apparent Km for ubiquinol-2 in ubiquinol-cytochrome c reductase. When mitoplasts or submitochondrial particles are exposed to a horseradish peroxidase conjugate of the Fab' fragment of anti-Mr 13,400 antibodies, peroxidase activity is found mainly in the submitochondrial particles preparation; little activity is detected in mitoplasts. This suggests that the Mr 13,400 protein is extruded toward the matrix side of the membrane.

背景与目标： : 通过涉及Triton X-100和尿素增溶，磷酸钙-纤维素柱色谱在不同ph下，丙酮沉淀，从牛心线粒体泛醇-细胞色素c还原酶中分离出含有Mr 13,400蛋白 (亚基VI)，磷脂和泛醌的制剂，和癸酰基-N-甲基葡糖酰胺-胆酸钠提取。该制剂中的蛋白质对应于在sch ä gger等人的十二烷基硫酸钠-聚丙烯酰胺凝胶电泳系统中解析的泛醇-细胞色素c还原酶的亚基VI (1987，FEBS Lett. 21，161-168)，并且具有与Wakabayashi等人报道的Mr 13,400蛋白相同的氨基酸序列 (1985，J. Biol. Chem. 260，337-343)。制剂中存在的磷脂和泛醌与Mr 13,400蛋白共纯化但不是固有成分。该制剂在恢复脱脂的泛醇-细胞色素c还原酶的活性方面具有与游离磷脂制剂相同的效力和行为。抗Mr 13,400的抗体仅与Mr 13,400蛋白和含有它的复合物反应。它们不抑制完整的，脂质充足的泛醇-细胞色素c还原酶。然而，当脱脂的泛醇-细胞色素c还原酶在用磷脂重建之前与抗体孵育时，观察到恢复活性的55% 降低，表明Mr 13,400蛋白的催化位点相关表位被掩埋在磷脂环境中。抗Mr 13,400的抗体导致泛醇-细胞色素c还原酶中ubiquinol-2的表观Km增加。当mitoposal或线粒体颗粒暴露于抗Mr 13,400抗体的Fab' 片段的辣根过氧化物酶缀合物时，过氧化物酶活性主要存在于线粒体颗粒制剂中; 在mitoposal中检测到的活性很少。这表明Mr 13,400蛋白向膜的基质侧挤出。

BACKGROUND & AIMS: Cytochrome bo is a member of the heme-copper terminal oxidase superfamily and serves as a four-subunit ubiquinol oxidase in the aerobic respiratory chain of Escherichia coli. To probe the location and structural properties of the ubiquinol oxidation site, we isolated and characterized five or 10 spontaneous mutants resistant to either 2,6-dimethyl-1,4-benzoquinone, 2,6-dichloro-4-nitrophenol, or 2,6-dichloro-4-dicyanovinylphenol, the potent competitive inhibitors for the oxidation of ubiquinol-1 [Sato-Watanabe, M., Mogi, T., Miyoshi, H., Iwamura, H., Matsushita, K., Adachi, O., and Anraku, Y. (1994) J. Biol. Chem. 269, 28899-28907]. Analyses of the growth yields and the ubiquinol-1 oxidase activities of the mutant membranes showed that the mutations increased the degree of the resistance to the selecting compounds. Notably, several mutants showed the cross-resistance. These data indicate that the binding sites for substrate and the competitive inhibitors are partially overlapped in the ubiquinol oxidation site. All the mutations were linked to the expression vector, and 23 mutations examined were all present in the C-terminal hydrophilic domain (Pro96-His315) of subunit II. Sequencing analysis revealed that seven mutations examined are localized near both ends of the cupredoxin fold. Met248Ile, Ser258Asn, Phe281Ser, and His284Pro are present in a quinol oxidase-specific (Qox) domain and proximal to low-spin heme b in subunit I and the lost CuA site in subunit II, whereas Ile129Thr, Asn198Thr, and Gln233His are rather scattered in a three-dimensional structure and closer to transmembrane helices of subunit II. Our data suggest that the Qox domain and the CuA end of the cupredoxin fold provide the quinol oxidation site and are involved in electron transfer to the metal centers in subunit I.

背景与目标： 细胞色素bo是血红素铜末端氧化酶超家族的成员，在大肠杆菌的有氧呼吸链中充当四亚基泛醇氧化酶。为了探究泛醇氧化位点的位置和结构性质，我们分离并鉴定了5个或10个对2,6-二甲基-1,4-苯醌，2,6-二氯-4-硝基苯酚或2,6-二氯-4-二氰基苯酚具有抗性的自发突变体，ubiquinol-1的有效竞争抑制剂 [Sato-Watanabe，M.，Mogi，T.，三好，H.，岩村，H.，松下，K.，足立，O.，和安乐，Y. (1994) J. Biol. Chem. 269，28899-28907]。对突变膜的生长产量和ubiquinol-1氧化酶活性的分析表明，突变增加了对选择化合物的抗性程度。值得注意的是，几个突变体显示出交叉抗性。这些数据表明，底物和竞争性抑制剂的结合位点在泛醇氧化位点部分重叠。所有突变均与表达载体连接，并且所检查的23个突变均存在于亚基II的C末端亲水结构域 (Pro96-His315) 中。测序分析显示，所检查的七个突变位于cupredoxin折叠的两端附近。Met248Ile，Ser258Asn，Phe281Ser和His284Pro存在于喹啉氧化酶特异性 (Qox) 结构域中，并且靠近亚基I中的低自旋血红素b和亚基II中丢失的CuA位点，而Ile129Thr，Asn198Thr，gln233His相当分散在三维结构中，更接近亚基II的跨膜螺旋。我们的数据表明，cupredoxin折叠的Qox结构域和CuA末端提供了quinol氧化位点，并参与了向亚基I中的金属中心的电子转移。

BACKGROUND & AIMS: The cytochrome bo ubiquinol oxidase from Escherichia coli is a five-subunit enzyme which is a member of the superfamily of heme-copper respiratory oxidases. Three of the subunits (I, II, and III) are homologous to the three mitochondrial encoded subunits of the eukaryotic aa3-type cytochrome c oxidase. Subunits, I, II, and III of the eukaryotic oxidase contain 12, 2, and 7 putative transmembrane spans, respectively. The hydropathy profiles of the subunits of most other members of this oxidase superfamily are consistent with these structures. However, subunit I from the E. coli oxidase contains 15 transmembrane spans, with one additional span at the N-terminus and two additional spans at the C-terminus in comparison to the eukaryotic oxidase. The additional transmembrane helix at the N-terminus predicts that the amino terminal residue should be on the periplasmic side of the membrane. By deleting the intergenic region between the cyoA and cyoB genes, an in-frame fusion between subunit II (cyoA) and subunit I (cyoB) was generated. This links the C-terminus of subunit II, known to be on the periplasmic side of the membrane, to the N-terminus of subunit I. The resulting oxidase is fully active, and supports the toplogical folding pattern previously suggested for subunit I with the N-terminus in the periplasm. Whereas subunit I of the E. coli oxidase has two additional membrane-spanning helices at the C-terminus, subunit III has two fewer helices than does the corresponding subunit III of the eukaryotic oxidase.(ABSTRACT TRUNCATED AT 250 WORDS)

背景与目标： 来自大肠杆菌的细胞色素bo泛醇氧化酶是一种五亚基酶，是血红素铜呼吸氧化酶超家族的成员。三个亚基 (I，II和III) 与真核aa3-type细胞色素c氧化酶的三个线粒体编码亚基同源。真核氧化酶的亚基I，II和III分别包含12、2和7个推定的跨膜跨度。该氧化酶超家族大多数其他成员的亚基的亲水谱与这些结构一致。然而，与真核氧化酶相比，来自大肠杆菌氧化酶的亚基I包含15个跨膜跨度，在N末端增加一个跨度，在C末端增加两个跨度。N末端的附加跨膜螺旋预测氨基末端残基应在膜的周质侧。通过删除cyoA和cyoB基因之间的基因间区域，生成了亚基II (cyoA) 和亚基I (cyoB) 之间的框架内融合。这将亚基II的C端 (已知位于膜的周质侧) 连接到亚基I的N端。所得的氧化酶具有完全活性，并支持先前建议的亚基I在周质中具有N末端的顶折叠模式。大肠杆菌氧化酶的亚基I在C末端有两个额外的跨膜螺旋，而亚基III比真核氧化酶的相应亚基III少两个螺旋。(摘要截短于250字)

BACKGROUND & AIMS: STUDY OBJECTIVE:To assess the effects of fenofibrate therapy on concentrations of plasma ubiquinol-10 and ubiquinone-10-the reduced and oxidized forms, respectively, of coenzyme Q(10). DESIGN:Prospective, open-label, non-controlled study. SETTING:University clinic and laboratory. PATIENTS:Eighteen patients with hyperlipidemia and type 2 diabetes mellitus. INTERVENTION:Patients received fenofibrate 150 mg/day for 12 weeks. MEASUREMENTS AND MAIN RESULTS:Metabolic parameters were assessed 4, 8, and 12 weeks after the start of fenofibrate treatment. Plasma ubiquinol-10 and ubiquinone-10 levels were measured by reverse-phase high-performance liquid chromatography. At 4, 8, and 12 weeks, significant reductions in fasting triglyceride levels and significant increases in high-density lipoprotein cholesterol levels were noted. Total cholesterol, low-density lipoprotein cholesterol, fasting plasma glucose, and adiponectin levels, however, did not change significantly. Plasma ubiquinol-10 concentrations significantly increased after 8 and 12 weeks (p<0.05 for both), whereas ubiquinone-10 concentrations tended to decrease, especially at 12 weeks. CONCLUSION:Our findings suggest that fenofibrate may help produce energy or prevent oxidation by increasing plasma ubiquinol-10 concentration; this effect may protect against the development and progression of atherosclerosis. In addition, treatment with fenofibrate demonstrated a favorable effect on serum lipid parameters.

背景与目标：

BACKGROUND & AIMS: :Deletion of QCR9, the nuclear gene encoding subunit 9 of the mitochondrial cytochrome bc1 complex in Saccharomyces cerevisiae, results in inactivation of the bc1 complex and inability of the yeast to grow on non-fermentable carbon sources. The loss of bc1 complex activity is due to loss of electron transfer activity at the ubiquinol oxidase site (center P) in the complex. Electron transfer at the ubiquinone reductase site (center N), is unaffected by the loss of subunit 9, but the extent of cytochrome b reduction is diminished. This is the first instance in which a supernumerary polypeptide, lacking a redox prosthetic group, has been shown to be required for an electron transfer reaction within the cytochrome bc1 complex.

背景与目标： : QCR9 (酿酒酵母中线粒体细胞色素bc1复合物的编码亚基9的核基因) 的缺失，导致bc1复合物失活，并且酵母无法在不可发酵的碳源上生长。bc1复合物活性的丧失是由于复合物中泛醇氧化酶位点 (中心P) 的电子转移活性的丧失。泛醌还原酶位点 (中心N) 的电子转移不受亚基9损失的影响，但细胞色素b还原的程度减少了。这是第一个实例，其中缺少氧化还原假体基团的多余多肽已被证明是细胞色素bc1复合物内电子转移反应所必需的。

BACKGROUND & AIMS: :The R481 residue of cytochrome bo(3) ubiquinol oxidase from E. coli is highly conserved in the heme-copper oxidase superfamily. It has been postulated to serve as part of a proton loading site that regulates proton translocation across the protein matrix of the enzyme. Along these lines, proton pumping efficiency has been demonstrated to be abolished in many R481 mutants. However, R481Q in bo(3) from E. coli has been shown to be fully functional, implying that the positive charge of the arginine is not required for proton translocation [ Puustinen , A. and Wikstrom , M. ( 1999 ) Proc. Natl. Acad. Sci. U.S.A. 96 , 35 - 37 ]. In an effort to delineate the structural role of R481 in the bo(3) oxidase, we used resonance Raman spectroscopy to compare the nonfunctional R481L mutant and the functional R481Q mutant, to the wild type protein. Resonance Raman data of the oxidized and reduced forms of the R481L mutant indicate that the mutation introduces changes to the heme o(3) coordination state, reflecting a change in position and/or coordination of the Cu(B) located on the distal side of heme o(3), although it is approximately 10 A away from R481. In the reduced-CO adduct of R481L, the frequencies of the Fe-CO and C-O stretching modes indicate that, unlike the wild type protein, the Cu(B) is no longer close to the heme-bound CO. In contrast, resonance Raman data obtained from the various oxidation and ligation states of the R481Q mutant are similar to those of the wild type protein, except that the mutation causes an enhancement of the relative intensity of the beta conformer of the CO-adduct, indicating a shift in the equilibrium between the alpha and beta conformers. The current findings, together with crystallographic structural data of heme-copper oxidases, indicate that R481 plays a keystone role in stabilizing the functional structure of the Cu(B) site through a hydrogen bonding network involving ordered water molecules. The implications of these data on the proton translocation mechanism are considered.

背景与目标： : 来自大肠杆菌的细胞色素bo(3) 泛醇氧化酶的R481残基在血红素铜氧化酶超家族中高度保守。据推测，它是质子加载位点的一部分，该位点调节质子在酶的蛋白质基质上的转运。按照这些思路，已证明在许多R481突变体中都可以消除质子泵送效率。然而，来自大肠杆菌的bo(3) 中的R481Q已被证明具有完全功能，这意味着质子易位不需要精氨酸的正电荷 [Puustinen，A.和Wikstrom，M、 (1999) Proc. Natl. Acad. Sci. U.S.A.96,35-37]。为了描述R481在bo(3) 氧化酶中的结构作用，我们使用共振拉曼光谱法将非功能性R481L突变体和功能性R481Q突变体与野生型蛋白进行了比较。R481L突变体的氧化和还原形式的共振拉曼数据表明，该突变引入了血红素o(3) 配位状态的变化，反映了位于血红素o(3) 远端的Cu(B) 的位置和/或配位的变化，尽管它与r481相距约10 A。在R481L的还原CO加合物中，Fe-CO和c-o拉伸模式的频率表明，与野生型蛋白不同，Cu(B) 不再接近血红素结合的CO。相反，从R481Q突变体的各种氧化和连接状态获得的共振拉曼数据与野生型蛋白质的共振拉曼数据相似，只是该突变导致共加合物的 β 构象体的相对强度增强，表明 α 和 β 构象异构体之间的平衡发生了变化。当前的发现以及血红素-铜氧化酶的晶体学结构数据表明，R481通过涉及有序水分子的氢键网络在稳定Cu(B) 位点的功能结构中起着关键作用。考虑了这些数据对质子易位机制的影响。

BACKGROUND & AIMS: :Dietary restriction (DR) is a robust intervention that extends both health span and life span in many organisms. Ubiquinol and ubiquinone represent the reduced and oxidized forms of coenzyme Q (CoQ). CoQ plays a central role in energy metabolism and functions in several cellular processes including gene expression. Here we used the model organism Caenorhabditis elegans to determine level and redox state of CoQ and expression of genes in response to DR. We found that DR down-regulates the steady-state expression levels of several evolutionary conserved genes (i.e. coq-1) that encode key enzymes of the mevalonate and CoQ-synthesizing pathways. In line with this, DR decreases the levels of total CoQ and ubiquinol. This CoQ-reducing effect of DR is obvious in adult worms but not in L4 larvae and is also evident in the eat-2 mutant, a genetic model of DR. In conclusion, we propose that DR reduces the level of CoQ and ubiquinol via gene expression in the model organism C. elegans.

背景与目标： : 饮食限制 (DR) 是一种强有力的干预措施，可以延长许多生物的健康寿命和寿命。泛醌和泛醌代表辅酶q (CoQ) 的还原和氧化形式。CoQ在能量代谢中起着核心作用，并在包括基因表达在内的几个细胞过程中发挥作用。在这里，我们使用秀丽隐杆线虫的模式生物来确定CoQ的水平和氧化还原状态以及响应DR的基因表达。我们发现DR下调了几个进化保守基因 (即coq-1) 的稳态表达水平，这些基因编码甲羟戊酸和辅酶q合成途径的关键酶。与此一致，DR降低了总CoQ和泛醇的水平。DR的这种降低CoQ的作用在成年蠕虫中很明显，但在L4幼虫中不明显，在DR的遗传模型eat-2突变体中也很明显。总之，我们建议DR通过模式生物秀丽隐杆线虫中的基因表达降低CoQ和泛醇的水平。