EC Number |
Substrates |
Organism |
Products |
Reversibility |
---|
1.17.98.4 | CO2 + reduced benzyl viologen |
- |
Escherichia coli |
formate + benzyl viologen |
- |
r |
1.17.98.4 | formate + acceptor |
- |
Escherichia coli |
CO2 + reduced acceptor |
- |
? |
1.17.98.4 | formate + acceptor |
formate dehydrogenase H (FDHH) catalyses the first step in the formate hydrogen lyase (FHL) system |
Escherichia coli |
CO2 + reduced acceptor |
- |
? |
1.17.98.4 | formate + acceptor |
the transfer of the formate proton, 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. Under normal physiological conditions, when electron flow is not limited by the terminal acceptor of electrons, the energy released upon oxidation of Mo(IV) centers by the Fe4S4 is used for deprotonation of YH(formate) and transfer of H+(formate) against the thermodynamic potential. This mechanism of proton release from FDH(Se) may play a physiological role in delivery of the formate proton H+(formate) to hydrogenase 3, which is the natural terminal acceptor of electrons for FDH(Se) |
Escherichia coli |
CO2 + reduced acceptor |
- |
? |
1.17.98.4 | formate + acceptor |
the reinterpretation of the crystal structure suggests a new reaction mechanism: In step I, formate binds directly to Mo, displacing Se-Cys140. In step II, the alpha-proton from formate may be transferred to the nearby His141 that acts as general base. In this step the CO2 molecule can be released and two electrons transferred to Mo. Alternatively, step II may involve a selenium-carboxylated intermediate. In step III, electrons from Mo(IV) are transferred via the [4Fe-4S] center to an external electron acceptor and the catalytic cycle is completed |
Escherichia coli |
CO2 + reduced acceptor |
- |
? |
1.17.98.4 | formate + benzyl viologen |
- |
Escherichia coli |
CO2 + reduced benzyl viologen |
- |
? |
1.17.98.4 | formate + benzyl viologen |
- |
Archaeoglobus fulgidus |
CO2 + reduced benzyl viologen |
- |
? |
1.17.98.4 | formate + benzyl viologen |
- |
Escherichia coli |
CO2 + reduced benzyl viologen |
- |
r |
1.17.98.4 | formate + benzyl viologen |
the transfer of the formate proton, 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. Under normal physiological conditions, when electron flow is not limited by the terminal acceptor of electrons, the energy released upon oxidation of Mo(IV) centers by the Fe4S4 is used for deprotonation of YH(formate) and transfer of H+(formate) against the thermodynamic potential. This mechanism of proton release from FDH(Se) may play a physiological role in delivery of the formate proton H+(formate) to hydrogenase 3, which is the natural terminal acceptor of electrons for FDH(Se) |
Escherichia coli |
CO2 + reduced benzyl viologen |
- |
? |
1.17.98.4 | formate + benzyl viologen |
FDH-H remains essentially unchanged when deuteroformate is used as a substrate |
Escherichia coli |
CO2 + reduced benzyl viologen |
- |
? |