Abstract

The pH profile (log k vs. pH) of the reactions of poly-L-lysine (PL) with a series of aryl acetates and aryl methyl carbonates in aqueous solution show the same conformational changes as those determined by potentiometric titrations. When PL is a random coil, the most probable mechanism for the reactions studied is through the formation of a tetrahedral intermediate and its breakdown to products as the rate-determining step. The tetrahedral intermediate is stabilized by a hydrogen bond interaction between the nitro groups in the substrate and the NH group of the principal chain or some NH 2 groups of the lateral chains. Copyright © 2007 John Wiley & Sons, Ltd.