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	Effects of selenium on the structure and function of recombinant human S-adenosyl-L-methionine dependent arsenic (+3 oxidation state) methyltransferase in E-coli
	Geng, Zhirong ; Song, Xiaoli ; Xing, Zhi ; Geng, Jinlong ; Zhang, Sichun ; Zhang, Xinrong ; Wang, Zhilin
	2010-10-12 ; 2010-10-12
关键词	Recombinant human arsenic (+3 oxidation state) methyltransferase Circular dichroism spectrum Selenium Structure-function relationship Noncompetitive inhibitor RAT-LIVER CYTOSOL INCLUSION BODY FORMATION TRYPTOPHAN FLUORESCENCE DRINKING-WATER CIRCULAR-DICHROISM BILIARY-EXCRETION DIETARY SELENIUM ARSINIUM ION IN-VITRO METHYLATION Biochemistry & Molecular Biology Chemistry, Inorganic & Nuclear
中文摘要	The effects of Se-IV on the structure and function of recombinant human arsenic (+3 oxidation state) methyltransferase (AS3MT) purified from the cytoplasm of Escherichia coli were studied. The coding region of human AS3MT complementary DNA was amplified from total RNA extracted from HepG2 cell by reverse transcription PCR. Soluble and active human AS3MT was expressed in the E. coli with a Trx fusion tag under a lower induction temperature of 25 degrees C. Spectra (UV-vis, circular dichroism, and fluorescence) were first used to probe the interaction of Se-IV and recombinant human AS3MT and the structure-function relationship of the enzyme. The recombinant human AS3MT had a secondary structure of 29.0% alpha-helix, 23.9% beta-pleated sheet, 17.9% beta-turn, and 29.2% random coil. When Se-IV was added, the content of the alpha -helix did not change, but that of the beta-pleated sheet increased remarkably in the conformation of recombinant human AS3MT. Se-IV inhibited the enzymatic methylation of inorganic As-III in a concentration-dependent manner. The IC50 value for Se-IV was 2.38 mu M. Double-reciprocal (1/V vs. 1/[inorganic As-III]) plots showed Se-IV to be a noncompetitive inhibitor of the methylation of inorganic As-III by recombinant human AS3MT with a K-i value of 2.61 mu M. We hypothesized that Se-IV interacts with the sulfhydryl group of cysteine(s) in the structural residues rather than the cysteines of the active site (Cys156 and Cys206). When Se-IV was combined with cysteine(s) in the structural residues, the conformation of recombinant human AS3MT changed and the enzymatic activity decreased. Considering the quenching of tryptophan fluorescence, Cys72 and/or Cys226 are deduced to be primary targets for Se-IV.
语种	英语 ; 英语
出版者	SPRINGER ; NEW YORK ; 233 SPRING ST, NEW YORK, NY 10013 USA
内容类型	期刊论文
源URL	[http://hdl.handle.net/123456789/81103]
专题	清华大学
推荐引用方式 GB/T 7714	Geng, Zhirong,Song, Xiaoli,Xing, Zhi,et al. Effects of selenium on the structure and function of recombinant human S-adenosyl-L-methionine dependent arsenic (+3 oxidation state) methyltransferase in E-coli[J],2010, 2010.
APA	Geng, Zhirong.,Song, Xiaoli.,Xing, Zhi.,Geng, Jinlong.,Zhang, Sichun.,...&Wang, Zhilin.(2010).Effects of selenium on the structure and function of recombinant human S-adenosyl-L-methionine dependent arsenic (+3 oxidation state) methyltransferase in E-coli..
MLA	Geng, Zhirong,et al."Effects of selenium on the structure and function of recombinant human S-adenosyl-L-methionine dependent arsenic (+3 oxidation state) methyltransferase in E-coli".(2010).

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