EC Number   |
Metals/Ions |
Reference |
|---|
    1.17.98.4 | selenium |
anaerobic oxidation of formate by Methanococcus vannielii is catalyzed by two readily separable formate dehydrogenases. One of these is a 105000 Da protein that contains molybdenum, iron, and acid-labile sulfide, but not selenium. The other is a high molecular weight complex composed of selenoprotein and molybdo-iron sulfur protein subunits |
727803 |
| 1.17.98.4 | Mo |
contains bis-molybdopterin guanine dinucleotide |
695650 |
| 1.17.98.4 | Molybdenum |
contains molybdenum |
742756 |
| 1.17.98.4 | Fe |
each mole of enzyme contains 3.3 gatoms of iron |
698686 |
| 1.17.98.4 | Mo |
enzyme contains a bis-molybdopterin guanine dinucleotide cofactor. EPR spectroscopy of the Mo(V) state indicates a square pyramidal geometry analogous to that of the Mo(IV) center. The strongest ligand field component is likely the single axial Se atom producing a ground orbital configuration Mo(dxy). The Mo-Se bond is estimated to be covalent to the extent of 17-27% of the unpaired electron spin density residing in the valence 4s and 4p selenium orbitals, based on comparison of the scalar and dipolar hyperfine components to atomic 77Se. Two electron oxidation of formate by the Mo(VI) state converts Mo to the reduced Mo(IV) state with the formate proton, H+(formate), transferring to a nearby base Y-. Transfer of one electron to the Fe4S4 center converts Mo(IV) to the EPR detectable Mo(V) state. The Y- is located within magnetic contact to the [Mo-Se] center, as shown by its strong dipolar 1Hf hyperfine couplings. Photolysis of the formate-induced Mo(V) state abolishes the 1Hf hyperfine splitting from YH(formate), suggesting photoisomerization of this group or phototransfer of the proton to a more distant proton acceptor group A-. The minor effect of photolysis on the 77Se-hyperfine interaction with [77Se] selenocysteine suggests that the Y- group is not the Se atom, but instead might be the imidazole ring of the His141 residue which is located in the putative substrate-binding pocket close to the [Mo-Se] center. It is proposed that the transfer of H+(formate) from formate to the active site base Y- is thermodynamically coupled to two-electron oxidation of the formate molecule, thereby facilitating formation of CO2 |
696191 |
| 1.17.98.4 | Se |
formate dehydrogenase H contains selenocysteine as an integral amino acid. Selenium of formate dehydrogenase H is directly involved in formate oxidation |
701023 |
| 1.17.98.4 | Se |
Mo of the molybdopterin is coordinated with the Se atom of selenocysteine |
701024 |
| 1.17.98.4 | Fe |
Mo(IV)- and the reduced FeS cluster-containing form of the enzyme is crystallized and this can be converted into Mo(VI)- and oxidized FeS cluster form upon oxidation |
698704 |
| 1.17.98.4 | Mo |
Mo(IV)- and the reduced FeS cluster-containing form of the enzyme is crystallized and this can be converted into Mo(VI)- and oxidized FeS cluster form upon oxidation |
698704 |
| 1.17.98.4 | Mo |
molybdopterin containg enzyme, Mo is coordinated with the Se atom of selenocysteine |
701024 |
