Mercuric reductase is responsible for detoxifying and volatilising mercury as Hg0. The catalytic centre is activated when in the diol form, rather than the disulfide. This preliminary, activating reduction step is proposed to involve another NADPH molecule. Both forms are present under physiological conditions and have been identified by structural data [PMID:16114877, PMID:2067577].
Defined by 4 residues: CYS:A-42CYS:A-47CYS:A_2-464CYS:A_2-465