Catalytic effect of CTAB on the interaction of dipeptide glycyl-tyrosine (Gly-Tyr)‎ with ninhydrin

Abstract EN

The effect of cationic micelles of cetyltrimethylammonium bromide (CTAB) on the interaction of dipeptide glycyl-tyrosine (Gly-Tyr) with ninhydrin under varying conditions has been studied spectrophotometrically at 70 °C and pH 5.0.

The reaction followed first-and fractionalorder kinetics with respect to [Gly-Tyr] and [ninhydrin], respectively.

Increase in total concentration of CTAB from 0 to 70 * 10¯3 mol dm¯3 resulted in an increase in the pseudo-first-order rate constant (kw) by a factor of ca.

3.

Quantitative kinetic analysis of kw-[CTAB] data was performed on the basis of pseudo-phase model of the micelles (proposed by Menger and Portnoy and developed by Bunton) and Piszkiewicz model.

A possible mechanism has been proposed and the kinetic data have been used to evaluate the micellar binding constants KS (268 mol¯1 dm3 for Gly-Tyr) and KN (64 mol¯1 dm¯3 for ninhydrin).