Arsenite oxidase

Arsenite oxidase (Aio), from the bacteria Alcaligenes faecalis, is an enzyme that metabolizes arsenic as part of the organism's energy generation process. This enzyme is part of the larger microbial metabolism that allows bacteria to survive in environments with high concentrations of arsenic.

Function

Arsenite oxidase catalyzes the oxidation of arsenite (As(III)) to arsenate (As(V)). This reaction is coupled with the reduction of an electron acceptor such as oxygen or nitrate. The overall reaction can be represented as follows:

As(III) + acceptor → As(V) + reduced acceptor

The enzyme is a heterodimer composed of a large subunit (AioA) and a small subunit (AioB). The large subunit contains a molybdenum cofactor and a 3Fe-4S cluster, while the small subunit contains a Rieske 2Fe-2S cluster and has been proposed to function as an electron transfer subunit.

Role in Bioremediation

Arsenite oxidase has potential applications in bioremediation, as it can convert the more toxic and mobile arsenite to the less toxic and less mobile arsenate in contaminated water. This enzymatic process can therefore help to reduce the impact of arsenic contamination in the environment.

See Also

• Arsenic contamination of groundwater
• Bioremediation
• Oxidoreductase