Dihydrogen arsenite | 855923-98-7

• 分子结构分类: 无机化合物 - 混合金属/非金属化合物 - 各种混合金属/非金属
• 英文名称: Dihydrogen arsenite
• 英文别名: dihydrogen arsorite
• CAS: 855923-98-7
• 化学式: AsH₂O₃
• 分子量: 124.936
• InChiKey: AQLMHYSWFMLWBS-UHFFFAOYSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  -2.68
• 重原子数：
  4
• 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：
  63.5
• 氢给体数：
  2
• 氢受体数：
  3

反应信息

• 作为反应物：
  描述：

  水 、 Dihydrogen arsenite 以 水 为溶剂， 生成
  参考文献：
  名称：

  Kläning; Bielski, Benon H. J.; Sehested, Inorganic Chemistry, 1989, vol. 28, # 14, p. 2717 - 2724

  摘要：

  DOI：
• 作为产物：
  描述：

  L-cysteine residue 、 arseno-mycothiol 、 氢(+1)阳离子 生成 S-mycothiol-L-cysteine residue 、 Dihydrogen arsenite
  参考文献：
  名称：

  Arsenate Reductase, Mycothiol, and Mycoredoxin Concert Thiol/Disulfide Exchange

  摘要：

  We identified the first enzymes that use mycothiol and mycoredoxin in a thiol/disulfide redox cascade. The enzymes are two arsenate reductases from Corynebacterium glutamicum (Cg ArsC1 and Cg ArsC2), which play a key role in the defense against arsenate. In vivo knockouts showed that the genes for Cg_ArsC1 and Cg_ArsC2 and those of the enzymes of the mycothiol biosynthesis pathway confer arsenate resistance. With steady-state kinetics, arsenite analysis, and theoretical reactivity analysis, we unraveled the catalytic mechanism for the reduction of arsenate to arsenite in C. glutamicum. The active site thiolate in Cg_ArsCs facilitates adduct formation between arsenate and mycothiol. Mycoredoxin, a redox enzyme for which the function was never shown before, reduces the thiol-arseno bond and forms arsenite and a mycothiol-mycoredoxin mixed disulfide. A second molecule of mycothiol recycles mycoredoxin and forms mycothione that, in its turn, is reduced by the NADPH-dependent mycothione reductase. Cg_ArsCs show a low specificity constant of similar to 5 M-1 s(-1), typically for a thiol/disulfide cascade with nucleophiles on three different molecules. With the in vitro reconstitution of this novel electron transfer pathway, we have paved the way for the study of redox mechanisms in actinobacteria.

  DOI：

  10.1074/jbc.m900877200

文献信息

• Enzymic Methylation of Arsenic Compounds: Assay, Partial Purification, and Properties of Arsenite Methyltransferase and Monomethylarsonic Acid Methyltransferase of Rabbit Liver
  作者：Robert Zakharyan、Yuan Wu、Gregory M. Bogdan、H. Vasken Aposhian

  DOI：10.1021/tx00050a006

  日期：1995.12

  present time for these enzyme activities being on different protein molecules. Neither arsenate, selenate, selenite, or selenide are methylated by the purified enzyme preparations. Results from the use of crude extracts, often called cytosol, to study the properties of these methyltransferases dealing with arsenic species should be viewed with caution since such crude extracts contain inhibiting and

  已经开发出一种利用放射性S-腺苷甲硫氨酸（SAM）的快速，准确的体外测定方法，用于兔肝甲基转移酶对亚砷酸和单甲基ar酸酯（MMA）的甲基化。通过使用氯仿萃取，离子交换色谱，TLC或HPLC分离，鉴定和测量反应产物，已经验证了该测定法。已从兔肝中纯化了约2000倍的与该途径有关的酶，亚砷酸甲基转移酶和MMA甲基转移酶。凝胶电泳后，获得具有两个酶活性的单条带。纯化的亚砷酸甲基转移酶和单甲基ar磺酸甲基转移酶的最适pH分别为8.2和8.0。硫醇S-腺苷甲硫氨酸 对于部分纯化的亚砷酸盐甲基转移酶（催化一甲基ar磺酸盐的合成）而言，亚砷酸盐是必需的。催化单甲基ar酸酯甲基化为二甲基ar酸酯的另一种酶活性也需要SAM和巯基。尽管亚砷酸甲基转移酶和单甲基砷酸甲基转移酶具有不同的底物，最适pH和底物的饱和浓度，但仍无法确定两种活性是存在于一个蛋白质分子上还是存在于不同的蛋白质分子上。通过凝胶排阻色谱法测定
• Enzymatic Methylation of Arsenic Compounds. VII. Monomethylarsonous Acid (MMAIII) Is the Substrate for MMA Methyltransferase of Rabbit Liver and Human Hepatocytes
  作者：Robert A. Zakharyan、Felix Ayala-Fierro、William R. Cullen、Dean M. Carter、H.Vasken Aposhian

  DOI：10.1006/taap.1999.8687

  日期：1999.7

  species to dimethylarsinic acid (DMA). The monomethyl compound containing arsenic in an oxidation state of +3 has been proposed as an intermediate. Using highly purified arsenic methyltransferase from rabbit liver and the partially purified enzyme from Chang human liver hepatocytes, the activity of methylarsonic acid (MMAV) and methylarsonous acid (MMAIII) as a substrate has been characterized by Michaelis-Menten

  无机砷被一些（但不是全部）动物物种甲基化为二甲基砷酸（DMA）。已经提出了氧化态为+3的含砷的单甲基化合物作为中间体。使用来自兔肝的高度纯化的砷甲基转移酶和来自人类肝肝细胞的部分纯化的酶，Michaelis-Menten动力学表征了甲基characterized酸（MMAV）和甲基ar酸（MMAIII）作为底物的活性。兔肝酶对MMAIII的亲和力（Km = 0.92 x 10（-5）M）比MMAV（Km = 7.0 x 10（-5）M）大，因为Km越小，亲和力越大。此外，二硫醇，还原的硫辛酸或二硫苏糖醇在满足酶的硫醇需求方面似乎比GSH更具活性。尽管研究人员无法通过外科手术切除的人类肝脏检测到砷甲基转移酶，但现已确定其在常人肝细胞中的存在。使用来自昌人类肝细胞的MMAIII甲基转移酶，MMAIII的Km为3.04 x 10（-6），与兔肝酶的Km并无太大差异。
• A Novel S-Adenosyl-l-methionine:Arsenic(III) Methyltransferase from Rat Liver Cytosol
  作者：Shan Lin、Qing Shi、F. Brent Nix、Miroslav Styblo、Melinda A. Beck、Karen M. Herbin-Davis、Larry L. Hall、Josef B. Simeonsson、David J. Thomas

  DOI：10.1074/jbc.m110246200

  日期：2002.3

  S-Adenosyl-l-methionine (AdoMet):arsenic(III) methyltransferase, purified from liver cytosol of adult male Fischer 344 rats, catalyzes transfer of a methyl group from AdoMet to trivalent arsenicals producing methylated and dimethylated arsenicals. The kinetics of production of methylated arsenicals in reaction mixtures containing enzyme, AdoMet, dithiothreitol, glutathione (GSH), and arsenite are consistent

  S-腺苷-1-蛋氨酸（AdoMet）：砷（III）甲基转移酶，是从成年雄性Fischer 344大鼠的肝细胞溶质中纯化的，催化甲基从AdoMet转移到三价砷中，产生甲基化和二甲基化的砷。在包含酶，AdoMet，二硫苏糖醇，谷胱甘肽（GSH）和亚砷酸盐的反应混合物中生成甲基化砷的动力学与以下方案一致：在方案中，由亚砷酸盐生产的单甲基化砷是第二个甲基化反应的底物，产生了二甲基化砷。该蛋白质的mRNA可以预测一个369个氨基酸的残基蛋白质（分子量41056），该蛋白质包含常见的甲基转移酶序列基序。其序列类似于在人和小鼠组织中表达的Cyt19，一种假定的甲基转移酶。逆转录聚合酶链反应可在大鼠组织和HepG2细胞（一种将亚砷酸和甲基砷酸甲基化的人类细胞系）中检测到S-腺苷-1-甲硫氨酸：砷（III）甲基转移酶mRNA。在UROtsa细胞中未检测到S-腺苷-1-甲硫氨酸：砷（III）甲基转移酶mRNA
• Purification and characterization of the respiratory arsenate reductase of Chrysiogenes arsenatis
  作者：Torsten Krafft、Joan M. Macy

  DOI：10.1046/j.1432-1327.1998.2550647.x

  日期：1998.8

  Chrysiogenes arsenatis is the only bacterium known that respires anaerobically using arsenate as the terminal electron acceptor and the respiratory substrate acetate as the electron donor. During growth, the arsenate is reduced to arsenite; the reduction is catalyzed by an arsenate reductase. This study describes the purification and characterization of a respiratory arsenate reductase (Arr). The enzyme consists of two subunits with molecular masses of 87 kDa (ArrA) and 29 kDa (ArrB), and is a heterodimer α1β1 with a native molecular mass of 123 kDa. The arsenate reductase contains molybdenum, iron, acid‐labile sulfur and zinc as cofactor constituents. The Km of the enzyme for arsenate is 0.3 mM and the Vmax is 7013 μmol arsenate reduced  min−1  mg protein−1. Nitrate, sulfate, selenate and fumarate cannot serve as alternative electron acceptors for the arsenate reductase. Synthesis of the protein is regulated, as arsenate must be present during growth for the enzyme to be fully induced. The N‐terminus of ArrA is similar to a number of procaryotic molybdenum‐containing polypeptides (e.g. the formate dehydrogenases H and N of Escherichia coli). The N‐terminus of ArrB is similar to iron‐sulfur proteins. The respiratory arsenate reductase of C. arsenatis is different from the non‐respiratory arsenate reductases of E. coli and Staphylococcus aureus.

  Chrysiogenes arsenatis 是唯一已知的能够在无氧条件下利用砷酸盐作为终电子受体、乙酸盐作为呼吸底物进行呼吸作用的细菌。在生长过程中，砷酸盐被还原为亚砷酸盐；这一还原过程由砷酸盐还原酶催化。本研究描述了呼吸型砷酸盐还原酶（Arr）的纯化和特性。该酶由两个亚基组成，分子质量分别为87 kDa（ArrA）和29 kDa（ArrB），形成一个异二聚体α1β1，其天然分子质量为123 kDa。砷酸盐还原酶含有钼、铁、酸不稳定硫和锌作为辅因子成分。该酶对砷酸盐的米氏常数（Km）为0.3 mM，最大反应速率（Vmax）为7013 μmol砷酸盐还原 min−1 mg蛋白−1。硝酸盐、硫酸盐、硒酸盐和富马酸盐不能作为砷酸盐还原酶的替代电子受体。该酶的合成受到调控，因为在生长过程中必须存在砷酸盐才能使酶充分诱导。ArrA的N端与多种原核生物来源的含钼多肽（例如大肠杆菌中的H型和N型甲酸脱氢酶）相似。ArrB的N端与铁硫蛋白相似。C. arsenatis的呼吸型砷酸盐还原酶与大肠杆菌和金黄色葡萄球菌中的非呼吸型砷酸盐还原酶不同。
• All intermediates of the arsenate reductase mechanism, including an intramolecular dynamic disulfide cascade
  作者：Joris Messens、José C. Martins、Karolien Van Belle、Elke Brosens、Aline Desmyter、Marjan De Gieter、Jean-Michel Wieruszeski、Rudolph Willem、Lode Wyns、Ingrid Zegers

  DOI：10.1073/pnas.132142799

  日期：2002.6.25

  The mechanism of pI258 arsenate reductase (ArsC) catalyzed arsenate reduction, involving its P-loop structural motif and three redox active cysteines, has been unraveled. All essential intermediates are visualized with x-ray crystallography, and NMR is used to map dynamic regions in a key disulfide intermediate. Steady-state kinetics of ArsC mutants gives a view of the crucial residues for catalysis. ArsC combines a phosphatase-like nucleophilic displacement reaction with a unique intramolecular disulfide bond cascade. Within this cascade, the formation of a disulfide bond triggers a reversible “conformational switch” that transfers the oxidative equivalents to the surface of the protein, while releasing the reduced substrate.

  pI258砷酸还原酶（ArsC）催化的砷酸还原机制已经揭示，其中涉及其P-环结构基序和三个氧化还原活性半胱氨酸。通过X射线晶体学可视化所有必要的中间体，并使用NMR来映射关键二硫键中的动态区域。ArsC突变体的稳态动力学给出了催化关键残基的视角。ArsC将类磷酸酶的亲核置换反应与独特的分子内二硫键级联结合。在此级联中，二硫键的形成触发可逆的“构象开关”，将氧化当量转移至蛋白质表面，同时释放还原底物。