Regioselective nitration of phenol induced by catalytic antibodies.
Catalytic antibodies with a metalloporphyrin cofactor represent a new generation of biocatalysts tailored for selective oxidations. Thus monoclonal antibodies, 3A3, were raised against microperoxidase 8 (MP8), and the corresponding 3A3-MP8 complexes were shown previously to have a high peroxidase activity. This paper shows that those complexes also catalyzed efficiently the nitration of phenol into 2- and 4-nitrophenol by NO2- in the presence of H2O2. pH dependence studies suggested that no amino acid from the antibody protein participated in the heterolytic cleavage of the O-O bond of H2O2. The inhibition of the reaction by cyanide and radical scavengers suggested a MP8-mediated peroxidase-like mechanism, involving the reduction of high-valent iron-oxo species by NO2- and phenol producing, respectively, NO2* and phenoxy radicals, which then reacted to give nitrophenols. Finally, the antibody protein appears to have two major roles: (i) it protects MP8 toward oxidative degradations and (ii) it induces a regioselectivity of the reaction toward the formation of 2-nitrophenol.
Ricoux
Rémy
R
Laboratoire de Chimie Bioorganique et bioinorganique, FRE 2127 CNRS, Institut de Chimie Moleculaire d-Orsay, Bât. 420, Université de Paris-sud XI, 91405, Orsay Cedex, France.
Girgenti
Elodie
E
Sauriat-Dorizon
Hélène
H
Blanchard
Dominique
D
Mahy
Jean-Pierre
JP
D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D017151:Antibodies, Catalytic / Q000737:chemistry* / Q000378:metabolism; D000911:Antibodies, Monoclonal / Q000737:chemistry* / Q000378:metabolism; D002384:Catalysis; D003486:Cyanides / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D016166:Free Radical Scavengers / Q000494:pharmacology; D005609:Free Radicals / Q000737:chemistry; D005978:Glutathione / Q000494:pharmacology; D006736:Horses; D006861:Hydrogen Peroxide / Q000737:chemistry; D007501:Iron / Q000378:metabolism; D007700:Kinetics; D051379:Mice; D008807:Mice, Inbred BALB C; D009566:Nitrates / Q000737:chemistry* / Q000378:metabolism; D010544:Peroxidases / Q000737:chemistry / Q000378:metabolism; D019800:Phenol / Q000737:chemistry* / Q000378:metabolism; D012977:Sodium Nitrite / Q000737:chemistry; D013237:Stereoisomerism
D017151:Antibodies, Catalytic; D000911:Antibodies, Monoclonal; D003486:Cyanides; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D005609:Free Radicals; D009566:Nitrates; D019800:Phenol; D006861:Hydrogen Peroxide; D007501:Iron; D010544:Peroxidases; C021799:microperoxidase; D005978:Glutathione; D012977:Sodium Nitrite; D000111:Acetylcysteine