EC - Arsenite methyltransferase

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IntEnz Enzyme Nomenclature


Accepted name:
arsenite methyltransferase
Other names:
S-adenosyl-L-methionine:arsenic(III) methyltransferase
S-adenosyl-L-methionine:methylarsonite As-methyltransferase
methylarsonite methyltransferase
Systematic name:
S-adenosyl-L-methionine:arsenite As-methyltransferase



An enzyme of the biotransformation pathway that forms dimethylarsinate from inorganic arsenite and arsenate. It methylates arsenite to form methylarsonate, Me-AsO3H2, which is reduced by EC, methylarsonate reductase, to methylarsonite, Me-As(OH)2. Methylarsonite is also a substrate for this enzyme (EC, which converts it into the much less toxic compound dimethylarsinate (cacodylate), Me2As(O)-OH.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , DIAGRAM , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UM-BBD , UniPathway
Structural data: CSA , EC2PDB
Gene Ontology: GO:0030791


  1. Zakharyan, R.A. and Aposhian, H.V.
    Enzymatic reduction of arsenic compounds in mammalian systems: The rate-limiting enzyme of rabbit liver arsenic biotransformation is MMA(V) reductase.
    Chem. Res. Toxicol. 121 : 1278-1283 (1999). [PMID: 10604879]
  2. Zakharyan, R.A., Ayala-Fierro, F., Cullen, W.R., Carter, D.M. and Aposhian, H.V.
    Enzymatic methylation of arsenic compounds. VII. Monomethylarsonous acid (MMAIII) is the substrate for MMA methyltransferase of rabbit liver and human hepatocytes.
    Toxicol. Appl. Pharmacol. 158 : 9-15 (1999). [PMID: 10387927]
  3. Zakharyan, R.A., Wildfang, E. and Aposhian, H.V.
    Enzymatic methylation of arsenic compounds. III. The marmoset and tamarin, but not the rhesus, monkeys are deficient in methyltransferases that methylate inorganic arsenic.
    Toxicol. Appl. Pharmacol. 140 : 77-84 (1996). [PMID: 8806872]
  4. Zakharyan, R.A., Wu, Y., Bogdan, G.M. and Aposhian, H.V.
    Enzymatic methylation of arsenic compounds: assay, partial purification, and properties of arsenite methyltransferase and monomethylarsonic acid methyltransferase of rabbit liver.
    Chem. Res. Toxicol. 8 : 1029-1038 (1995). [PMID: 8605285]
  5. Lin, S., Shi, Q., Nix, F.B., Styblo, M., Beck, M.A., Herbin-Davis, K.M., Hall, L.L., Simeonsson, J.B. and Thomas, D.J.
    A novel S-adenosyl-L-methionine:arsenic(III) methyltransferase from rat liver cytosol.
    J. Biol. Chem. 277 : 10795-10803 (2002). [PMID: 11790780]

[EC created 2000, modified 2003]