Kinetics and Mechanism of L-Tryptophan Oxidation by Chloramine-T in Basic Medium: A Spectrofluorometric Study

One of the greatest challenges in oxidation research today is the determination of in v ivo o xidative stresses. In this investigation, the spectrofluorometry is used to monitor the kinetics of chloramine-T (CAT) o xidation of L-tryptophan (Trp) in basic solutions. The Trp-CAT reaction progress has been monitored at λmax = 485 n m (after using the excitation wavelength of 360 n m) over the temperature range, 293-313 K. The redo x reaction follows a first-order dependence of the rate each on (CAT) and (Trp), and an inverse fractional-order on (OH-). Variat ions of the ionic strength and the solvent dielectric constant have no effect on the rate. An addition of the reduction product of CAT, p-toluenesulfonamide, to the reaction mixture also has no influence on the rate. Based on the temperature effect, activation parameters are evaluated. A mechanis m consistent with the observed kinetic and activation data has been proposed and the rate-law derived.