|Gene:||4hbD||Accession Number: G-10251 (MetaCyc)|
Species: Clostridium kluyveri
Subunit composition of
4-hydroxybutyrate dehydrogenase = [4hbD]2
4-hydroxybutyrate dehydrogenase (NAD) = 4hbD
4-hydroxybutyrate dehydrogenase (NAD) activity has been measured in cell extracts of Clostridium kluyveri grown in the presence of either acetate or succinate. Activity was found only in cells grown with succinate, and was 350 nmoles/mg/min for the reduction, and 70 nmoles/mg/min for the oxidation, suggesting that the reaction occurs mostly in the reduction direction (formation of 4-hydroxybutanoate) [Wolff93].
The 4hbD gene, encoding the enzyme, has been cloned and expressed in Escherichia coli [Sohling96]. This enzyme was purified 42-fold under anaerobic conditions to homogeneity, and found to be a homodimer [Wolff95]. The protein contains two atoms of Cu and one atom of Fe per monomeric unit.
Molecular Weight of Polypeptide: 41.756 kD (from nucleotide sequence), 41.6 kD (experimental) [Wolff95 ]
Molecular Weight of Multimer: 86.0 kD (experimental) [Wolff95]
Enzymatic reaction of: 4-hydroxybutyrate dehydrogenase
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 direction in which it was curated.
This reaction is reversible.
In Pathways: succinate fermentation to butyrate
When co-expressed in E. coli with the sucD gene, activity in cell extracts was 475 mU/mg [Sohling96]. The enzyme exhibits maximum activity at pH 6.1 for the reduction of succinic semialdehyde and at pH 9.4 for the oxidization of 4-hydroxybutanoate [Wolff95].
pH(opt): 6.1 [Wolff95]
Sohling93: Sohling B, Gottschalk G (1993). "Purification and characterization of a coenzyme-A-dependent succinate-semialdehyde dehydrogenase from Clostridium kluyveri." Eur J Biochem 212(1);121-7. PMID: 8444151
Wolff93: Wolff RA, Urben GW, O'Herrin SM, Kenealy WR (1993). "Dehydrogenases involved in the conversion of succinate to 4-hydroxybutanoate by Clostridium kluyveri." Appl Environ Microbiol 59(6);1876-82. PMID: 8328804
Wolff95: Wolff RA, Kenealy WR (1995). "Purification and characterization of the oxygen-sensitive 4-hydroxybutanoate dehydrogenase from Clostridium kluyveri." Protein Expr Purif 6(2);206-12. PMID: 7606170
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