EC 1.20.4.2     
Accepted name: methylarsonate reductase
Reaction: methylarsonate + 2 glutathione = methylarsonite + glutathione disulfide + H2O
Glossary: methylarsonite = methylarsonous acid
cacodylic acid = dimethylarsinic acid
Other name(s): MMA(V) reductase
Systematic name: methylarsonate:glutathione oxidoreductase
Comments: The product, methylarsonite, is biologically methylated by EC 2.1.1.137, arsenite methyltransferase, to form cacodylic acid.
References:
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. 12 (1999) 1278–1283. [PMID: 10604879]
[EC 1.20.4.2 created 2000 as EC 1.97.1.7, transferred 2001 to EC 1.20.4.2, modified 2003]