The enzyme, characterized from the bacterium Streptomyces thioluteus, catalyses an early step in the biosynthesis of the antibiotic aureothin. It contains a carboxylate-bridged binuclear non-heme iron cluster. The native electron donor has not been identified, but is likely an iron-sulfur protein. The reaction mechanism involves formation of an extremely stable peroxo intermediate that catalyses three two-electron oxidations via a hydroxylamine and dihydroxylamine intermediates. cf. EC 1.14.99.67, N-[1-(4-aminophenyl)-1,3-dihydroxypropan-2-yl]-2,2-dichloroacetamide N-oxygenase.
The expected taxonomic range for this enzyme is: Streptomyces thioluteus
The enzyme, characterized from the bacterium Streptomyces thioluteus, catalyses an early step in the biosynthesis of the antibiotic aureothin. It contains a carboxylate-bridged binuclear non-heme iron cluster. The native electron donor has not been identified, but is likely an iron-sulfur protein. The reaction mechanism involves formation of an extremely stable peroxo intermediate that catalyses three two-electron oxidations via a hydroxylamine and dihydroxylamine intermediates. cf. EC 1.14.99.67, N-[1-(4-aminophenyl)-1,3-dihydroxypropan-2-yl]-2,2-dichloroacetamide N-oxygenase.
Substrates: the yield of the final product 4-nitrobenzoate is 37.2% when equimoles of reductants phenazine methosulfate and 4-aminobenzoic acid and 4 equimoles of ascorbate are used Products: -
the Fe2 II/II cluster in AurF reacts with O2 in the absence of substrate to form a stable (half-life of about 7 min at 20°C) adduct with spectroscopic properties characteristic of a peroxo-Fe2 III/III complex
in-frame deletion of aurF yields a mutant, in which both N-oxidation activity and aureothin production is abolished. Aureothin biosynthesis in the mutant can be fully restored upon supplying the culture with synthetic 4-nitrobenzoate
peroxo-Fe2 III-III AurF oxidizes 4-hydroxylaminobenzoate Ar-NHOH. This reaction proceeds through to the Ar-NO2 final product, a four-electron oxidation, and produces Fe2 II-II AurF, with which O2 can combine to regenerate peroxo-Fe2 III-III AurF. Conversion of Ar-NHOH to Ar-NO2 requires only a single equivalent of O2 is fully catalytic in the absence of exogenous reducing equivalents
reduced AurF's electronic and geometric structures are poised to react rapidly with O2. The active peroxo intermediate has a protonated peroxo bridge. The protonation activates peroxide for electrophilic/single-electron-transfer reactivity
the Fe2 II/II cluster in AurF reacts with O2 in the absence of substrate to form a stable (half-life of about 7 min at 20°C) adduct with spectroscopic properties characteristic of a peroxo-Fe2 III/III complex. The intermediate complex decays rapidly (half-life of about 0.005 s at 20°C) when mixed with stoichiometric 4-aminobenzoate. Over 80% conversion of 4-aminobenzoate to 4-nitrobenzoate is observed upon addition of less than 0.3 equivalents of the amine substrate to a solution of the intermediate peroxo-Fe2 III/III complex. The complex might effect all three steps in the sequence
the key oxygenated intermediates in diiron arylamine oxygenases AurF and CmlI, EC 1.14.99.67, so-called P, are uniformly hydroperoxo species having similar structures rather than the believed peroxo species. A diferric-hydroperoxo P is proposed to be able to promote the arylamine N-oxygenation with highly accessible kinetics
Please wait a moment until the data is sorted. This message will disappear when the data is sorted.
CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
structure at 2.1 A resolution shows a homodimer with a binuclear manganese cluster and an iron content of about 15%. An additional histidine residue in the coordination sphere causes the preference for manganese over iron. There is no oxo-bridge
Mechanistic studies on the conversion of arylamines into arylnitro compounds by aminopyrrolnitrin oxygenase identification of intermediates and kinetic studies