Accepted Name |
arsenite methyltransferase
|
Alternative Name(s) |
methylarsonite methyltransferase |
Reaction catalysed |
- [thioredoxin]-dithiol + arsenic triglutathione + 2 H2O + S-adenosyl-L-methionine <=> [thioredoxin]-disulfide + 3 glutathione + H(+) + methylarsonous acid + S-adenosyl-L-homocysteine
- 2 [thioredoxin]-dithiol + arsenic triglutathione + H2O + 2 S-adenosyl-L-methionine <=> 2 [thioredoxin]-disulfide + dimethylarsinous acid + 3 glutathione + 2 H(+) + 2 S-adenosyl-L-homocysteine
- 3 [thioredoxin]-dithiol + arsenic triglutathione + 3 S-adenosyl-L-methionine <=> 3 [thioredoxin]-disulfide + 3 glutathione + 3 H(+) + 3 S-adenosyl-L-homocysteine + trimethylarsine
|
Comment(s) |
- An enzyme responsible for synthesis of trivalent methylarsenical
antibiotics in microbes or detoxification of inorganic arsenous acid
in animals.
- The in vivo substrate is arsenic triglutathione or similar thiol
(depending on the organism), from which the arsenic is transferred to
the enzyme forming bonds with the thiol groups of three cysteine
residues via a disulfide bond cascade pathway.
- Most of the substrates undergo two methylations and are converted to
dimethylarsinous acid.
- 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.
|
Cross-references |
BRENDA | 2.1.1.137 |
EC2PDB | 2.1.1.137 |
ExplorEnz | 2.1.1.137 |
PRIAM enzyme-specific profiles | 2.1.1.137 |
KEGG Ligand Database for Enzyme Nomenclature | 2.1.1.137 |
IUBMB Enzyme Nomenclature | 2.1.1.137 |
IntEnz | 2.1.1.137 |
MEDLINE | Find literature relating to 2.1.1.137 |
MetaCyc | 2.1.1.137 |
Rhea expert-curated reactions | 2.1.1.137 |
UniProtKB/Swiss-Prot |
|
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