tailieunhanh - Báo cáo khoa học: Microperoxidase 8 catalysed nitrogen oxides formation from oxidation of N-hydroxyguanidines by hydrogen peroxide

Nitric oxide (NO) is a potent intra- and intercellular mes-senger involved in the control of vascular tone, neuronal signallingandhost response to infection. Inmammals,NOis synthesized by oxidation ofL-arginine catalysed by heme-proteins called NO-synthases with intermediate formation of N x -hydroxy-L-arginine (NOHA). NOHA and some hydroxyguanidines have been shown to be able to deliver nitrogen oxides including NO in the presence of various oxidative systems. | Eur. J. Biochem. 270 47-55 2003 FEBS 2003 doi Microperoxidase 8 catalysed nitrogen oxides formation from oxidation of V-hydroxyguanidines by hydrogen peroxide Remy Ricoux1 Jean-Luc Boucher2 Dominique Mandon3 Yves-Michel Frapart2 Yann Henry4 Daniel Mansuy2 and Jean-Pierre Mahy1 1 Laboratoire de Chimie Bioorganique et Bioinorganique Institut de Chimie Moleculaire d Orsay Université Paris-Sud XI Orsay France 2Universite R. Descartes Paris France 3Institut LeBel Strasbourg France 4Institut Curie-Recherche Universite Paris-Sud XI Orsay France Nitric oxide NO is a potent intra- and intercellular messenger involved in the control of vascular tone neuronal signalling and host response to infection. In mammals NO is synthesized by oxidation of L-arginine catalysed by hemeproteins called NO-synthases with intermediate formation of N -hydroxy-L-arginine NOHA . NOHA and some hydroxyguanidines have been shown to be able to deliver nitrogen oxides including NO in the presence of various oxidative systems. In this study NOHA and a model compound N- 4-chlorophenyl -N -hydroxyguanidine were tested for their abilityto generate NO in the presence of a haemprotein model microperoxidase 8 MP8 and hydrogen peroxide. Nitrite and nitrate production along with selective formation of 4-chlorophenylcyanamide was observed from incubations of N- 4-chlorophenyl -N -hydroxyguanidine in the presence of MP8 and hydrogen peroxide. In the case of NOHA the corresponding cyana mide A -cyano-L-ornithine was too unstable under the conditions used and L-citrulline was the onlyproduct identified. A NO-specific conversion of 2- 4-carboxyphe-nyl -4 4 5 5-tetramethylimidazoline-1-oxyl 3-oxide to 2- 4-carboxyphenyl -4 4 5 5-tetramethylimidazoline-1-oxyl and formation of MP8-Fe-NO complexes were observed by EPR spectroscopy and low-temperatLire UV visible spectroscopy respectively. These results clearly demonstrate the formation of nitrogen oxides including NO from the .

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