|Gene:||hnr||Accession Number: G-10435 (MetaCyc)|
Species: Eubacterium barkeri
Subunit composition of
6-hydroxynicotinate reductase = [Hnr]4
6-hydroxynicotinate reductase subunit = Hnr
6-Hydroxynicotinate reductase has been purified under anaerobic conditions from nicotinate-grown cells of Eubacterium barkeri. The enzyme is a homotetrameric [Fe-S] flavoprotein that contains up to 9.3 Fe and 6-8 acid-labile sulfur atoms per monomer. The flavin is covalently bound. [Alhapel06].
The apparent molecular mass of the subunit was determined by SDS-PAGE [Alhapel06] .
Molecular Weight of Polypeptide: 53.097 kD (from nucleotide sequence), 53.0 kD (experimental) [Alhapel06 ]
Enzymatic reaction of: 6-hydroxynicotinate reductase
Synonyms: 6-oxotetrahydronicotinate dehydrogenase, 6-hydroxynicotinic reductase
EC Number: 18.104.22.168
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.
The reaction is favored in the opposite direction.
6-Hydroxynicotinate reductase catalyzes the reversible reduction of 6-hydroxynicotinic acid to the 4-5- dihydro derivative. It requires reduced ferredoxin as the electron donor in vivo. Reduced methyl viologen can serve as electron donor in vitro. The enzyme is unstable in the presence of air [Holcenberg69a].
pH(opt): 6.5 [Holcenberg69a]
Alhapel06: Alhapel A, Darley DJ, Wagener N, Eckel E, Elsner N, Pierik AJ (2006). "Molecular and functional analysis of nicotinate catabolism in Eubacterium barkeri." Proc Natl Acad Sci U S A 103(33);12341-6. PMID: 16894175
Holcenberg69a: Holcenberg JS, Tsai L (1969). "Nicotinic acid metabolism. IV. Ferredoxin-dependent reduction of 6-hydroxynicotinic acid to 6-oxo-1,4,5,6-tetrahydronicotinic acid." J Biol Chem 244(5);1204-11. PMID: 5767303
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