Transfer of nitric oxide from nitrovasodilators to free thiols--evidence of two distinct stages |
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Authors: | Dasgupta Tara P Aquart Danielle V |
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Institution: | Department of Chemistry, University of the West Indies, Mona Campus, Kingston 7, Jamaica. tara.dasgupta@uwimona.edu.jm |
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Abstract: | Two distinct stages, which can be monitored spectrophotometrically, have been observed for the first time in multiple reactions between thiol, such as l-cysteine and some well-known nitrovasodilators, namely S-nitroso-N-acetyl-d,l-penicillamine (SNAP), S-nitrosoglutathione (GSNO), and S-nitrosocaptopril (SNOCap) in aqueous solution (in the presence of EDTA). The first part of the reaction occurs at stopped-flow time scale ( approximately 10(-2)s(-1)) in one single step and has been found to be transnitrosation; followed by a slow decomposition of the products of the transnitrosation reaction with the formation of a variety of nitrogen products. Reactivity with regard to the first stage occurs in the order GSNO>SNAP>SNOCap. The second stage shows first-order rate constants of the order 10(-4)s(-1), although some degree of complexity exists in elucidating an accurate rate equation with which a comparative study could be done. |
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Keywords: | Nitrovasodilators Transnitrosation l-Cysteine" target="_blank">l-Cysteine d" target="_blank">S-Nitroso-N-acetyl-d l-penicillamine" target="_blank">l-penicillamine S-Nitrosoglutathione S-Nitrosocaptopril |
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