Species: Pseudomonas fluorescens ACB
This enzyme is an extradiol-type dioxygenase that catalyzes the conversion of benzene-1,4-diol to (2E,4Z)-4-hydroxy-6-oxohexa-2,4-dienoate. It is a novel member of the nonheme-iron(II)-dependent dioxygenase family. It did not show any significant amino acid sequence identity with known dioxygenases [Moonen08].
The native apparent molecular mass of this α2β2 heterotetrameric enzyme was determined by online size-exclusion chromatography/mass spectrometry to be 112.4 kDa, composed of an α subunit of 17.8 kDa and a β subunit of 38.3 kDa. The β subunit contains binding sites for Fe2+ and the competitive inhibitor 4-hydroxybenzoate. The spectral properties of the enzyme also suggested an extradiol-type dioxygenase [Moonen08a].
Molecular Weight: 112.4 kD (experimental) [Moonen08a ]
Enzymatic reaction of: hydroquinone 1,2-dioxygenase
Synonyms: hydroquinone 1.2-dioxygenase
EC Number: 126.96.36.199
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 physiologically favored in the direction shown.
In Pathways: 4-hydroxyacetophenone degradation
The enzyme catalyzed the ring cleavage of a wide range of hydroquinone substrates to produce the corresponding 4-hydroxymuconic semialdehydes. Use of the competitive inhibitor 4-hydroxybenzoate during purification prevented irreversible inactivation of the enzyme [Moonen08a].
The Km value was determined at pH 7.0, 25 °C. A variety of phenolic compounds inhibited the enzxyme [Moonen08a].
pH(opt): 7-8 [Moonen08a]
Synonyms: HapD, hydroquinone dioxygenase β subunit
|Gene:||hapD||Accession Number: G-14992 (MetaCyc)|
Molecular Weight: 38.403 kD (from nucleotide sequence)
Unification Links: UniProt:B1GRL9
Synonyms: hydroquinone dioxygenase α subunit
|Gene:||HapC||Accession Number: G-14991 (MetaCyc)|
Molecular Weight: 17.841 kD (from nucleotide sequence)
Unification Links: UniProt:B1GRL8
Moonen08: Moonen MJ, Kamerbeek NM, Westphal AH, Boeren SA, Janssen DB, Fraaije MW, van Berkel WJ (2008). "Elucidation of the 4-hydroxyacetophenone catabolic pathway in Pseudomonas fluorescens ACB." J Bacteriol 190(15);5190-8. PMID: 18502868
Moonen08a: Moonen MJ, Synowsky SA, van den Berg WA, Westphal AH, Heck AJ, van den Heuvel RH, Fraaije MW, van Berkel WJ (2008). "Hydroquinone dioxygenase from pseudomonas fluorescens ACB: a novel member of the family of nonheme-iron(II)-dependent dioxygenases." J Bacteriol 190(15);5199-209. PMID: 18502867
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