Mechanism and biological implications of the NO release of cis-[Ru(bpy)2L(NO)](n+) complexes: a key role of physiological thiols |
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Authors: | Silva Francisco O N Cândido Manuela C L Holanda Alda K M Diógenes Izaura C N Sousa Eduardo H S Lopes Luiz G F |
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Institution: | Universidade Federal do Ceará, Departamento de Química Orgânica e Inorgânica, Campus do Pici, Caixa Postal 6021, CEP 60455-760, Fortaleza, CE, Brazil |
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Abstract: | Nitric oxide (NO) has a critical role in several physiological and pathophysiological processes. In this paper, the reactions of the nitrosyl complexes of Ru(bpy)2L(NO)]n+ type, where L = SO32− and imidazole and bpy = 2,2′-bipiridine, with cysteine and glutathione were studied. The reactions with cysteine and glutathione occurred through the formation of two sequential intermediates, previously described elsewhere, Ru(bpy)2L(NOSR)]n+ and Ru(bpy)2L(NOSR)2] (SR = thiol) leading to the final products Ru(bpy)2L(H2O)]n+ and free NO. The second order rate constant for the second step of this reaction was calculated for cysteine k2(SR−) = (2.20 ± 0.12) × 109 M− 1 s− 1 and k2(RSH) = (154 ± 2) M− 1 s− 1 for L = SO32− and k2(SR−) = (1.30 ± 0.23) × 109 M− 1 s− 1 and k2(RSH) = (0.84 ± 0.02) M− 1 s− 1 for L = imidazole; while for glutathione they were k2(SR−) = (6.70 ± 0.32) × 108 M− 1 s− 1 and k2(RSH) = 11.8 ± 0.3 M− 1 s− 1 for L = SO32− and k2(SR−) = (2.50 ± 0.36) × 108 M− 1 s− 1 and k2(RSH) = 0.32 ± 0.01 M− 1 s− 1 for L = imidazole. In all reactions it was possible to detect the release of NO from the complexes, which it is remarkably distinct from other ruthenium metallocompounds described elsewhere with just N2O production. These results shine light on the possible key role of NO release mediated by physiological thiols in reaction with these metallonitrosyl ruthenium complexes. |
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Keywords: | Ruthenium nitrosyl complexes Nitric oxide release Reaction with thiols |
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