Dasgupta, T.P; Aquart, D.V
Author Affiliation, Ana.
Transfer of nitric oxide from nitrovasodilators to free thiols- : Evidence of two distinct stages
Biochemical and Biophysical Research Communications
Date of Publication
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.....