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2.1.1.137: arsenite methyltransferase

This is an abbreviated version!
For detailed information about arsenite methyltransferase, go to the full flat file.

Word Map on EC 2.1.1.137

Reaction

2 S-adenosyl-L-methionine +

arsenic triglutathione
+ 2 thioredoxin +
H2O
=
S-adenosyl-L-homocysteine
+
dimethylarsinous acid
+ 3 glutathione + 2 thioredoxin disulfide

Synonyms

AdoMet:arsenic(III) methyltransferase, arsenic (+3 oxidation state) methyltransferase, arsenic (+3 oxidation state)-methyltransferase, arsenic (+3) methyltransferase, arsenic (III) methyltransferase, arsenic (III) S-adenosylmethionine methyltransferase, arsenic methyltransferase Cyt19, arsenic(III) methyltransferase, arsenite (+3 oxidation state) methyltransferase, arsenite methyltransferase, arsenite S-adenosylmethionine methyltransferase, ArsM, ArsM protein, ArsM7B, As(III) methyltransferase, As(III) S-adenosylmethionine methyltransferase, As(III) SAM methyltransferase, AS3MT, AsIII S-adenosylmethionine methyltransferase, Cyr19, Cyt19, EC 2.1.1.138, hAS3MT, methylarsonite methyltransferase, N6AMT1, S-adenosyl-L-methionine:arsenic(III) methyltransferase, S-adenosyl-L-methionine:methylarsonite As-methyltransferase, S-adenosylmethionine dependent arsenic methyltransferase, [As(III)] methyltransferase

ECTree

     2 Transferases
         2.1 Transferring one-carbon groups
             2.1.1 Methyltransferases
                2.1.1.137 arsenite methyltransferase

Systematic Name

Systematic Name on EC 2.1.1.137 - arsenite methyltransferase

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SYSTEMATIC NAME
IUBMB Comments
S-adenosyl-L-methionine:arsenous acid As-methyltransferase
An enzyme responsible for synthesis of trivalent methylarsenical antibiotics in microbes [11] or detoxification of inorganic arsenous acid in animals. The in vivo substrate is arsenic triglutathione or similar thiol (depending on the organism) [6], from which the arsenic is transferred to the enzyme forming bonds with the thiol groups of three cysteine residues [10] via a disulfide bond cascade pathway [7, 8]. Most of the substrates undergo two methylations and are converted to dimethylarsinous acid [9]. However, a small fraction are released earlier as methylarsonous acid, and a smaller amount proceeds via a third methylation, resulting in the volatile product trimethylarsane. Methylation involves temporary oxidation to arsenic(V) valency, followed by reduction back to arsenic(III) valency using electrons provided by thioredoxin or a similar reduction system. The arsenic(III) products are quickly oxidized in the presence of oxygen to the corresponding arsenic(V) species.