Human monomethylarsonic acid (MMAV) reductase is a member of the glutathione-S-transferase superfamily
Human monomethylarsonic acid (MMAV) reductase is a member of the glutathione-S-transferase superfamily
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DOI：
10.1021/tx010052h
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发表时间：
2001-08-01
影响因子：
4.1
通讯作者：
Aposhian, HV
中科院分区：
文献类型：
--
作者：
Zakharyan, RA;Sampayo-Reyes, A;Aposhian, HV
由于砷的致癌性，饮用含有大量无机砷的水是一个世界性的重大公共卫生问题。然而，对无机砷毒性的具体机制的理解一直是难以捉摸的。我们现在已经部分纯化的无机砷代谢的限速酶，人肝MMA（V）还原酶，使用离子交换，分子排阻，和羟基磷灰石层析。当对最纯化的级分进行SDS-β-巯基乙醇-PAGE时，获得七条蛋白带。从凝胶上切下每条条带，通过LC-MS/MS进行测序，并根据SWISS-PROT和TrEMBL蛋白质序列数据库进行鉴定。人肝MMA（V）还原酶与最近发现的人谷胱甘肽-S-转移酶Omega类hGSTO 1-1 100%相同，超过我们分析的序列的92%。重组人GSTO 1 -1具有MMA（V）还原酶活性，Km和V-max值与人肝MMA（V）还原酶相当。部分纯化的人肝MMAV还原酶具有谷胱甘肽S-转移酶（GST）活性。MMA（V）还原酶活性被GST底物1-氯-2，4-二硝基苯和GST抑制剂脱氧胆酸盐竞争性抑制。最纯的人肝MMA（V）还原酶的蛋白质印迹分析显示一个带时，探测与hGSTO 1 -1抗血清。我们认为MMA（V）还原酶和hGSTO 1-1是相同的蛋白质。
The drinking of water containing large amounts of inorganic arsenic is a worldwide major public health problem because of arsenic carcinogenicity. Yet an understanding of the specific mechanism(s) of inorganic arsenic toxicity has been elusive. We have now partially purified the rate-limiting enzyme of inorganic arsenic metabolism, human liver MMA(V) reductase, using ion exchange, molecular exclusion, and hydroxyapatite chromatography. When SDS-beta -mercaptoethanol -PAGE was performed on the most purified fraction, seven protein bands were obtained. Each band was excised from the gel, sequenced by LC-MS/MS and identified according to the SWISS-PROT and TrEMBL Protein Sequence databases. Human liver MMA(V) reductase is 100% identical, over 92% of sequence that we analyzed, with the recently discovered human glutathione-S-transferase Omega class hGSTO 1-1. Recombinant human GSTO1-1 had MMA(V) reductase activity with K-m and V-max values comparable to those of human liver MMA(V) reductase. The partially purified human liver MMAV reductase had glutathione S-transferase (GST) activity. MMA(V) reductase activity was competitively inhibited by the GST substrate, 1-chloro 2,4-dinitrobenzene and also by the GST inhibitor, deoxycholate. Western blot analysis of the most purified human liver MMA(V) reductase showed one band when probed with hGSTO1-1 antiserum. We propose that MMA(V) reductase and hGSTO 1-1 are identical proteins.