EC Number   |
Reaction |
Reference |
|---|
    1.16.1.1 | Hg + NADP+ + H+ = Hg2+ + NADPH |
- |
- |
| 1.16.1.1 | Hg + NADP+ + H+ = Hg2+ + NADPH |
catalytic mechanisms of the flavoprotein MerA, overview |
744823 |
| 1.16.1.1 | Hg + NADP+ + H+ = Hg2+ + NADPH |
FAD mediates the transfer of electrons between NADPH and Hg2+ bound to an adjacent pair of cysteine thiols (C136 and C141) in the buried active site, while a second pair of cysteines (C558 and C559) on the C-terminal tail mediates transfer of Hg2+ from other protein and small molecule thiols in solution to the active site cysteines through a ligand exchange mechanism, structure-function study, overview |
714224 |
| 1.16.1.1 | Hg + NADP+ + H+ = Hg2+ + NADPH |
MerA possesses metallochaperone-like N-terminal domains (NmerA) tethered to its catalytic core domain by linkers. The NmerA domains interacts principally through electrostatic interactions with the core, leashed by the linkers so as to subdiffuse on the surface over an area close to the core C-terminal Hg(II)-binding cysteines |
744515 |
| 1.16.1.1 | Hg + NADP+ + H+ = Hg2+ + NADPH |
molecular mechanism of the Hg transfer is analyzed by quantum mechanical/molecular mechanical (QM/MM) calculations, and simulation. The transfer is nearly thermoneutral and passes through a stable tricoordinated intermediate that is marginally less stable than the two end states. For the overall process, Hg2+ is always paired with at least two thiolates and thus is present at both the C-terminal and catalytic binding sites as a neutral complex. Prior to Hg2+ transfer, C141 is negatively charged. As Hg2+ is transferred into the catalytic site, a proton is transferred from C136 to C559' while C558' becomes negatively charged, resulting in the net transfer of a negative charge over a distance of about 7.5 A. Thus, the transport of this soft divalent cation is made energetically feasible by pairing a competition between multiple Cys thiols and/or thiolates for Hg2+ with a competition between the Hg2+ and protons for the thiolates. Reaction mechansim, detailed overview |
744330 |
