Selenate | 14124-68-6

• 分子结构分类: 无机化合物 - 混合金属/非金属化合物 - 其他混合金属/非金属含氧阴离子化合物
• 英文名称: Selenate
• CAS: 14124-68-6
• 化学式: O4Se-2
• 分子量: 142.97
• InChiKey: QYHFIVBSNOWOCQ-UHFFFAOYSA-L

计算性质

• 辛醇/水分配系数(LogP)：
  -3.0
• 重原子数：
  5
• 可旋转键数：
  0
• 环数：
  0.0
• sp3杂化的碳原子比例：
  0.0
• 拓扑面积：
  80.3
• 氢给体数：
  0
• 氢受体数：
  4

反应信息

• 作为产物：
  描述：

  a quinone 、 水 、 亚硒酸盐 生成 a quinol 、 Selenate
  参考文献：
  名称：

  摘要：

  DOI：

文献信息

• Bacterial respiration of arsenic and selenium
  作者：John F. Stolz、Ronald S. Oremland

  DOI：10.1111/j.1574-6976.1999.tb00416.x

  日期：1999.10

  Oxyanions of arsenic and selenium can be used in microbial anaerobic respiration as terminal electron acceptors. The detection of arsenate and selenate respiring bacteria in numerous pristine and contaminated environments and their rapid appearance in enrichment culture suggest that they are widespread and metabolically active in nature. Although the bacterial species that have been isolated and characterized are still few in number, they are scattered throughout the bacterial domain and include Gram-positive bacteria, beta, gamma and epsilon Proteobacteria and the sole member of a deeply branching lineage of the bacteria, Chrysiogenes arsenatus. The oxidation of a number of organic substrates (i.e. acetate, lactate, pyruvate, glycerol, ethanol) or hydrogen can be coupled to the reduction of arsenate and selenate, but the actual donor used varies from species to species. Both periplasmic and membrane-associated arsenate and selenate reductases have been characterized. Although the number of subunits and molecular masses differs, they all contain molybdenum. The extent of the environmental impact on the transformation and mobilization of arsenic and selenium by microbial dissimilatory processes is only now being fully appreciated.

  砷和硒的氧化亚离子可用作微生物厌氧呼吸的终端电子受体。在许多原始和污染环境中检测到砷酸盐和硒酸盐呼吸细菌，且其在富集培养基中迅速出现，这表明它们在自然界中广泛存在且代谢活跃。尽管分离和鉴定的细菌种类仍然很少，但它们遍布整个细菌领域，包括革兰氏阳性菌、β、γ和ε变形杆菌以及细菌深分支谱系中的唯一成员——砷化金黄单胞菌。一些有机底物（如乙酸盐、乳酸、丙酮酸、甘油、乙醇）或氢的氧化可与砷酸盐和硒酸盐的还原作用相结合，但实际使用的供体因物种而异。胞外和膜结合砷酸盐和硒酸盐还原酶的特征已经确定。尽管亚基数量和分子质量不同，但它们都含有钼。现在人们才充分认识到环境对微生物异化过程中砷和硒的转化和迁移的影响程度。
• Involvement of a putative molybdenum enzyme in the reduction of selenate by Escherichia coli
  作者：Magali Bébien、Julia Kirsch、Vincent Méjean、André Verméglio

  DOI：10.1099/00221287-148-12-3865

  日期：2002.12.1

  Selenium oxyanions, particularly selenite, can be highly toxic to living organisms. Few bacteria reduce both selenate and selenite into the less toxic elemental selenium. Insights into the mechanisms of the transport and the reduction of selenium oxyanions in Escherichia coli were provided by a genetic analysis based on transposon mutagenesis. Ten mutants impaired in selenate reduction were analysed. Three of them were altered in genes encoding transport proteins including a porin, an inner-membrane protein and a sulfate carrier. Two mutants were altered in genes required for molybdopterin biosynthesis, strongly suggesting that the selenate reductase of E. coli is a molybdoenzyme. However, mutants deleted in various oxomolybdenum enzymes described so far in this species still reduced selenate. Finally, a mutant in the gene ygfK encoding a putative oxidoreductase was obtained. This gene is located upstream of ygfN and ygfM in the ygfKLMN putative operon. YgfN and YgfM code for a molybdopterin-containing enzyme and a polypeptide carrying a FAD domain, respectively. It is therefore proposed that the selenate reductase of E. coli is a structural complex including the proteins YgfK, YgfM and YgfN. In addition, all the various mutants were still able to reduce selenite into elemental selenium. This implies that the transport and reduction of this compound are clearly distinct from those of selenate.

  硒氧化阴离子，特别是亚硒酸盐，对生物体具有剧毒。很少有细菌能将亚硒酸盐和亚硒酸还原成毒性较低的元素硒。基于转座子诱变技术的遗传分析为大肠杆菌中硒氧化阴离子的转运和还原机制提供了见解。研究人员分析了10个亚硒酸盐还原缺陷突变体。其中3个突变体的转运蛋白编码基因发生了改变，包括一种孔蛋白、一种内膜蛋白和一种硫酸盐载体蛋白。两个突变体的钼蛋白生物合成所需基因发生了改变，这有力地表明大肠杆菌的亚硒酸盐还原酶是一种钼蛋白酶。然而，该物种中迄今描述的各种氧化钼酶缺失的突变体仍然能够还原亚硒酸盐。最后，研究人员获得了编码假定氧化还原酶的基因ygfK的突变体。该基因位于ygfN和ygfM上游的ygfKLMN假定操作子中。YgfN和YgfM分别编码一种含钼蛋白酶和一种携带FAD结构域的多肽。因此，研究人员提出大肠杆菌的亚硒酸盐还原酶是一种结构复合物，包括YgfK、YgfM和YgfN蛋白。此外，所有这些突变体仍然能够将亚硒酸盐还原成元素硒。这意味着这种化合物的转运和还原与亚硒酸盐的转运和还原明显不同。
• The terminal reductases for selenate and nitrate respiration in Thauera selenatis are two distinct enzymes
  作者：S A Rech、J M Macy

  DOI：10.1128/jb.174.22.7316-7320.1992

  日期：1992.11

  A number of approaches have been used to show that a recently isolated selenate-respiring bacterium, Thauera selenatis, is able to synthesize both a selenate reductase (SR) and a nitrate reductase (NR). (i) The pH optimum of the SR was found to be 6.0; that of the NR was 7.0. (ii) The presence of nitrate did not inhibit selenate reduction in selenate-grown cells. (iii) In cell extracts, the highest SR or NR activity was observed in cells grown with the respective electron acceptor. (iv) Mutants that were unable to grow with nitrate as the terminal electron acceptor and lacked NR activity were isolated; these mutants grew normally with selenate and synthesized SR. (v) The SR was found in the periplasmic space of the cell, whereas the NR was present in the cytoplasmic membrane. A hypothetical electron transport system involving the SR is described.

  已经使用了多种方法表明，最近分离的硒酸盐呼吸菌Thauera selenatis能够合成硒酸盐还原酶（SR）和硝酸盐还原酶（NR）。 (i) SR的最适pH为6.0; NR的最适pH为7.0。(ii) 存在硝酸盐不会抑制硒酸盐在硒酸盐生长的细胞中的还原。(iii) 在细胞提取物中，分别在使用相应电子受体生长的细胞中观察到最高的SR或NR活性。(iv) 分离了无法以硝酸盐作为末端电子受体生长且缺乏NR活性的突变体; 这些突变体在硒酸盐中正常生长并合成SR。(v) SR位于细胞的周质空间中，而NR存在于细胞膜中。描述了涉及SR的假设电子传递系统。
• Cloning and Sequencing of the Genes Encoding the Periplasmic-Cytochrome<i>B</i>-Containing Selenate Reductase of<i>Thauera selenatis</i>
  作者：Torsten Krafft、Ashley Bowen、Friedbert Theis、Joan M. Macy

  DOI：10.3109/10425170009015604

  日期：2000.1

  The periplasmic selenate reductase (Ser) of Thauera selennatis is a component of the electron transport chain catalyzing selenate reduction with acetate as the electron donor (i.e., selenate respiration). The purified enzyme consists of three subunits (SerA, SerB and SerC). Using transposon (i.e., Tn5) mutagenesis selenate reductase mutants were isolated. Junction fragments of DNA adjacent to the integrated Tn5 were used, together with oligonucleotides derived from the N-termini of SerA and SerB, to clone from a gene bank a DNA fragment that contained the corresponding genes. After sequencing, serA, serB and serC were identified by sequence comparison with the N-termini of the three subunits. The genes are arranged in the order serA, serB, serC; a fourth open reading frame (serD) in between, but overlapping serB and serC, is also present. The serA gene product contains an apparent leader peptide with a twin-arginine motif. The remainder of the translated amino acid sequence is similar to that of a number of prokaryotic molybdenum-containing enzymes (e.g., nitrate reductases and formate dehydrogenases of Escherichia coli). The serB gene product contains four cysteine clusters and is similar to various iron-sulfur protein subunits. The serC gene product contains a putative Sec-dependent leader peptide, but there are no similarities between the remainder of the translated protein and other protein subunits. The SerC contains two histidine and four methionine residues, and these may noncovalently bind heme b--which is a component of the active selenate reductase. The serD gene product encodes a putative protein that shows no significant sequence similarities to other proteins. However, the location of the serD within the other ser genes is similar to that of narJ within the E. coli narGHJI operon (nitrate reductase A); thus suggesting that the role of SerD may be similar to that of NarJ, which is a system-specific chaperone protein.
• Purification and Characterization of the Selenate Reductase from Thauera selenatis
  作者：Imke Schröder、Sabine Rech、Torsten Krafft、Joan M. Macy

  DOI：10.1074/jbc.272.38.23765

  日期：1997.9

  Thauera selenatis is one of two isolated bacterial species that can obtain energy by respiring anaerobically with selenate as the terminal electron acceptor. The reduction of selenate to selenite is catalyzed by a selenate reductase, previously shown to be located in the periplasmic space of the cell. This study describes the purification of the enzyme from T. selenatis grown anaerobically with selenate. The enzyme is a trimeric alpha beta gamma complex with an apparent M-r of 180,000. The alpha, beta, and gamma subunits are 96 kDa, 40 kDa, and 23 kDa, respectively, in size. The selenate reductase contains molybdenum, iron, and acid-labile sulfur as prosthetic group constituents. UV-visible absorption spectroscopy also revealed the presence of one cytochrome b per alpha beta gamma complex, The K-m for selenate was determined to be 16 mu M, and the V-max was 40 mu mol/min/mg of protein. The enzyme is specific for the reduction of selenate; nitrate, nitrite, chlorate, and sulfate were not reduced at detectable rates, These studies constitute the first description of a selenate reductase, which represents a new class of enzymes. The significance of this enzyme in relation to cell growth and energy generation is discussed.