A long-lived, substrate-hydroxylating peroxodiiron(III/III) intermediate in the amine oxygenase, AurF, from Streptomyces thioluteus.
The amine oxygenase AurF from Streptomyces thioluteus catalyzes the six-electron oxidation of p-aminobenzoate (pABA) to p-nitrobenzoate (pNBA). In this work, we have studied the reaction of its reduced Fe(2)(II/II) cofactor with O(2), which results in generation of a peroxo-Fe(2)(III/III) intermediate. In the absence of substrate, this intermediate is unusually stable (t(1/2) = 7 min at 20 degrees C), allowing for its accumulation to almost stoichiometric amounts. Its decay is accelerated approximately 10(5)-fold by the substrate, pABA, implying that it is the complex that effects the two-electron oxidation of the amine to the hydroxylamine. The nearly quantitative conversion of pABA to pNBA by solutions containing an excess of the intermediate suggests that it may also be competent for the two subsequent two-electron oxidations leading to the product.
Korboukh
Victoria Korneeva
VK
Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Li
Ning
N
Barr
Eric W
EW
Bollinger
J Martin
JM
Krebs
Carsten
C
D010129:4-Aminobenzoic Acid / Q000737:chemistry*; D002384:Catalysis; D004795:Enzyme Stability; D005290:Ferric Compounds / Q000737:chemistry*; D009579:Nitrobenzoates / Q000737:chemistry*; D010084:Oxidation-Reduction; D010105:Oxygenases / Q000737:chemistry*; D013302:Streptomyces / Q000201:enzymology*
D005290:Ferric Compounds; D009579:Nitrobenzoates; D010105:Oxygenases; D010129:4-Aminobenzoic Acid