Effect of added nucleophilic species on the rate of primary amino acid nitrosation

Abstract

The rate of primary amino acid nitrosation, both with and without the addition of nucleophilic species, has been studied using stopped-flow spectrophotometry. The rate of nitrosation in the presence of strong nucleophilic species such as thiocyanate and thiourea was shown to be much faster than nitrosation without the addition of a nucleophile. Rate constants were determined at 25 °C for reaction of the amino acids alanine, glycine, and valine with five common nitrosating agents. For the nitrosating agents nitrosyl chloride, nitrosyl bromide, and dinitrogen trioxide the rate of reaction was observed to approach the predicted encounter-controlled limit. However, for nitrosyl thiocyanate and S..