Regioselective nitration of phenol induced by catalytic antibodies |
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Authors: | Ricoux Rémy Girgenti Elodie Sauriat-Dorizon Hélène Blanchard Dominique Mahy Jean-Pierre |
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Institution: | (1) Laboratoire de Chimie Bioorganique et bioinorganique, FRE 2127 CNRS, Institut de Chimie Moléculaire d'Orsay, Université de Paris-sud XI, Bât. 420, 91405 Orsay Cedex, France;(2) Laboratoire de Biotechnologie, Etablissement de Transfusion Sanguine, 34, boulevard Jean Monnet, 44011 Nantes Cedex 01, France |
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Abstract: | 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. |
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Keywords: | Hemoabzymes catalytic antibodies peroxidases microperoxidase 8 nitrophenol |
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