Peptide kinetics. Part 10.—Kinetics of simultaneous hydrolysis and reversible sequence-inversion of some dipeptides in strong acid

Abstract

A quantitative study of the kinetics of simultaneous hydrolysis and reversible sequence-inversion of the dipeptides L-leucyl-L-tyrosine, L-tryosyl-L-leucine, L-leucyl-glycine, glycyl-L-leucine, L-alanyl-glycine, glycyl-L-alanine, L-valyl-glycine and gylcyl-L-valine in 2 M HCl is reported. Values of the first-order rate constants for both processes have been determined at several temperatures in the range 84.2–114.2°C and values of ΔH^≠ and ΔS^≠ calculated. The results are discussed in terms of conformation effects of the dipeptide side chains. Revised values of the rate constants for the acid-catalyzed hydrolysis of L-leucyl-glycyl-L-leucine and glycyl-L-leucyl-glycine are also reported.