Microperoxidase 8 catalysed nitrogen oxides formation from oxidation of N‐hydroxyguanidines by hydrogen peroxide

• Published in: European Journal of Biochemistry 2003-01, Vol.270 (1), p.47-55
• Main Authors: Ricoux, Rémy, Boucher, Jean‐Luc, Mandon, Dominique, Frapart, Yves‐Michel, Henry, Yann, Mansuy, Daniel, Mahy, Jean‐Pierre
• Format: Article
• Language: English
• Subjects: Arginine - analogs & derivatives; Arginine - chemistry; Arginine - metabolism; Benzoates - chemistry; Benzoates - metabolism; Catalysis; Chemical Sciences; Electron Spin Resonance Spectroscopy; Guanidines - chemistry; Guanidines - metabolism; Hydrogen Peroxide - chemistry; Hydrogen Peroxide - metabolism; Imidazoles - chemistry; Imidazoles - metabolism; iron nitrosyl complexes; microperoxidase 8; nitric oxide; Nitric Oxide - metabolism; nitric oxide synthase; N‐hydroxyguanidines; Oxidation-Reduction; Peroxidases - metabolism; Spectrophotometry, Ultraviolet; Temperature
• ISSN: 0014-2956; 1432-1033; 1432-1327
• DOI: 10.1046/j.1432-1033.2003.03358.x

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 Nω‐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 ability to 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 cyanamide, Nδ‐cyano‐L‐ornithine, was too unstable under the conditions used and l‐citrulline was the only product identified. A NO‐specific conversion of 2‐(4‐carboxyphenyl)‐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‐temperature UV/visible spectroscopy, respectively. These results clearly demonstrate the formation of nitrogen oxides including NO from the oxidation of exogenous hydroxyguanidines by hydrogen peroxide in the presence of a minienzyme such as MP8. The importance of the bioactivation of endogenous (NOHA) or exogenous N‐hydroxyguanidines by peroxidases of physiological interest remains to be established in vivo.