title: Identification of intermediate and product from methemoglobin-catalyzed oxidation of o-phenylenediamine in two-phase aqueous-organic system.
abstract: Methemoglobin (metHb) was used as a mimetic enzyme for peroxidase to catalyze the oxidation reaction of o-phenylenediamine (OPDA) with H2O2 functioning as an oxidant. A reaction intermediate was obtained in two-phase aqueous-organic system and an absorption peak at 710 nm was confirmed to be that of the intermediate in relation to OPDA. The isolated product and intermediate were characterized by UV-Vis and IR spectrophotometry and HPLC-tandem mass spectrometry. The results showed that the product is 2,3-diaminophenazine, the molecular mass of the intermediate is 212 daltons, and a conceivable structure of the intermediate is suggested. Combining the catalyzed reaction mechanism of peroxidase and our experimental results, a conceivable oxidation reaction mechanism of OPDA and H2O2 using metHb as catalyst is proposed.
authors.affiliation: College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, PR China.
authors.forename: De-Jia
authors.initials: DJ
authors.lastname: Li
authors.forename: Xi-Wen
authors.initials: XW
authors.lastname: Li
authors.forename: Yu-Xiang
authors.initials: YX
authors.lastname: Xie
authors.forename: Xiao-Qiang
authors.initials: XQ
authors.lastname: Cai
authors.forename: Guo-Lin
authors.initials: GL
authors.lastname: Zou
mesh_terms: D002384:Catalysis; D006861:Hydrogen Peroxide / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods; D008706:Methemoglobin / Q000737:chemistry*; D008956:Models, Chemical; D016877:Oxidants / Q000737:chemistry; D010084:Oxidation-Reduction; D010619:Phenazines / Q000032:analysis / Q000737:chemistry; D010655:Phenylenediamines / Q000737:chemistry*; D012997:Solvents; D013053:Spectrophotometry / Q000379:methods; D013696:Temperature
chemical_list: D016877:Oxidants; D010619:Phenazines; D010655:Phenylenediamines; D012997:Solvents; C054312:2,3-diaminophenazine; C034193:1,2-diaminobenzene; D008706:Methemoglobin; D006861:Hydrogen Peroxide