title: 2-Aminobenzoyl-CoA monooxygenase/reductase, a novel type of flavoenzyme. Studies on the stoichiometry and the course of the reaction.
abstract: The reaction catalyzed by 2-aminobenzoyl-coenzyme-A monooxygenase/reductase from a denitrifying Pseudomonas sp. has been investigated. 2-Aminobenzoyl-CoA and 2-amino[carboxy-14C]benzoyl-CoA were synthesized enzymatically using 2-aminobenzoyl-CoA synthetase from the same organism. The product was purified by chromatography and characterized by ultraviolet/visible and 1H-NMR spectroscopy. The conversion of 2-aminobenzoyl-CoA catalyzed by the monooxygenase/reductase requires NADH and oxygen, and yields at least two different products depending on the relative concentration of NADH. At [NADH] less than Km (40 microM), i.e. [NADH]/[2-aminobenzoyl-CoA] approximately 0.02-0.05, the main product is probably a hydroxylated derivative of 2-aminobenzoyl-CoA, which is characterized by an absorbance maximum around 375 nm. When [NADH]/[2-aminobenzoyl-CoA] approximately 2-5, the predominant product is a non-aromatic coenzyme A thioester (lambda max approximately 320 nm). The stoichiometry in this case is 2.1-2.4 mol NADH oxidized (mol oxygen consumed)-1 (mol 2-aminobenzoyl-CoA metabolized)-1. The product is extremely unstable in the acidic pH range and undergoes decarboxylation in a few minutes at pH less than 5. Some degree of stabilisation is obtained upon reduction with sodium borohydride, probably resulting in a further reduced non-aromatic coenzyme-A thioester.
authors.affiliation: Abteilung Angewandte Mikrobiologie, Universität Ulm, FRG.
authors.forename: R
authors.initials: R
authors.lastname: Buder
authors.forename: K
authors.initials: K
authors.lastname: Ziegler
authors.forename: G
authors.initials: G
authors.lastname: Fuchs
authors.forename: B
authors.initials: B
authors.lastname: Langkau
authors.forename: S
authors.initials: S
authors.lastname: Ghisla
mesh_terms: D002384:Catalysis; D055598:Chemical Phenomena; D002621:Chemistry; D002851:Chromatography, High Pressure Liquid; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D006900:Hydroxylation; D009682:Magnetic Resonance Spectroscopy; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D009243:NAD / Q000494:pharmacology; D010088:Oxidoreductases / Q000378:metabolism*; D010101:Oxygen Consumption; D011549:Pseudomonas / Q000201:enzymology*; D013053:Spectrophotometry
chemical_list: D009243:NAD; D006899:Mixed Function Oxygenases; D010088:Oxidoreductases; C062023:2-aminobenzoyl-CoA monooxygenase-reductase