1.17.98.4: formate dehydrogenase (hydrogenase)
This is an abbreviated version!
For detailed information about formate dehydrogenase (hydrogenase), go to the full flat file.
Word Map on EC 1.17.98.4
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1.17.98.4
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fhl
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hydrogenases
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nife-hydrogenase
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formate-dependent
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hycb
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selenopolypeptide
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molybdoenzyme
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h2-evolving
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biohydrogen
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h2-oxidizing
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54-dependent
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f0f1-atpase
- 1.17.98.4
- fhl
- hydrogenases
- nife-hydrogenase
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formate-dependent
- hycb
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selenopolypeptide
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molybdoenzyme
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h2-evolving
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biohydrogen
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h2-oxidizing
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54-dependent
- f0f1-atpase
Reaction
Synonyms
benzylviologen-linked formate dehydrogenase, EC 1.1.99.33, EC 1.17.99.7, Fdh-H, FDH-O, fdhF gene product, FDHH, formate dehydrogenase (formate-hydrogen-lyase-linked), formate dehydrogenase H, formate dehydrogenase O, formate hydrogenlyase, methylviologen-dependent formate dehydrogenase, molybdenum-containing formate dehydrogenase H
ECTree
1.17.98.4 formate dehydrogenase (hydrogenase)Advanced search results
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results (Substrates Products
Substrates Products on EC 1.17.98.4 - formate dehydrogenase (hydrogenase)
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SUBSTRATE 
PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
formate + HycB
CO2 + reduced HycB
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the hydrogenase 3 Fe-S subunit HycB may represent the electron transfer partner of FDH-H
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?
formate + acceptor
CO2 + reduced acceptor
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formate dehydrogenase H (FDHH) catalyses the first step in the formate hydrogen lyase (FHL) system
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?
formate + acceptor
CO2 + reduced acceptor
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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)
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?
formate + acceptor
CO2 + reduced acceptor
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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
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?
formate + benzyl viologen
CO2 + reduced benzyl viologen
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the enzyme may have a role in formate reuptake
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?
formate + benzyl viologen
CO2 + reduced benzyl viologen
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?
formate + benzyl viologen
CO2 + reduced benzyl viologen
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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)
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?
formate + benzyl viologen
CO2 + reduced benzyl viologen
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FDH-H remains essentially unchanged when deuteroformate is used as a substrate
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?
formate + benzyl viologen
CO2 + reduced benzyl viologen
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formate oxidation is not rate-limiting in the overall coupled reaction of formate oxidation and benzyl viologen reduction
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-
?
formate + benzyl viologen
CO2 + reduced benzyl viologen
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ping-pong bi-bi kinetic mechanism
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?
formate + oxidized coenzyme F420
CO2 + reduced coenzyme F420
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?
formate + oxidized coenzyme F420
CO2 + reduced coenzyme F420
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?
additional information
?
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Escherichia coli possesses two hydrogenases, Hyd-3 and Hyd-4. These, in conjunction with formate dehydrogenase H (Fdh-H), constitute distinct membrane-associated formate hydrogenlyases, FHL-1 and FHL-2, both catalyzing the decomposition of formate to H2 and CO2 during fermentative growth. FHL-1 is the major pathway at acidic pH. At alkaline pH formate increases an activity of Fdh-H and of Hyd-3 both but not of Hyd-4
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?
additional information
?
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hydrogenase 3 but not hydrogenase 4 is the major enzyme in hydrogen gas production by Escherichia coli formate hydrogenlyase at acidic pH and in the presence of external formate
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?
additional information
?
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physiological role of FSH-O is to ensure rapid adaptation during a shift from aerobiosis to anaerobiosis
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?
additional information
?
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the enzyme catalyzes carbon exchange between carbon dioxide and formate in the absence of other electron acceptors, confirming the ping-pong reaction mechanism
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?
additional information
?
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no activity with NADP+ or NAD+
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?
