Transfer of nitric oxide from nitrovasodilators to free thiols--evidence of two distinct stages.
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.
Dasgupta
Tara P
TP
Department of Chemistry, University of the West Indies, Mona Campus, Kingston 7, Jamaica. tara.dasgupta@uwimona.edu.jm
Aquart
Danielle V
DV
D009569:Nitric Oxide / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D014665:Vasodilator Agents / Q000737:chemistry*
D013438:Sulfhydryl Compounds; D014665:Vasodilator Agents; D009569:Nitric Oxide