Premium
Kinetic investigation of the effect of the amino acid side chains in the selective acidolysis of N ‐acyl‐ N ,α,α‐trialkyl glycine amides
Author(s) -
Jiang WeiQun,
PereiraLima Sílvia M. M. A.,
Ventura Cristina,
Costa Susana P. G.,
Albuquerque Lídia,
GonçalvesMaia Raquel,
Maia Hernâni L. S.
Publication year - 2005
Publication title -
journal of peptide science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 66
eISSN - 1099-1387
pISSN - 1075-2617
DOI - 10.1002/psc.673
Subject(s) - steric effects , chemistry , substituent , glycine , reaction rate constant , polar , side chain , stereochemistry , correlation coefficient , substrate (aquarium) , computational chemistry , medicinal chemistry , kinetics , amino acid , organic chemistry , biochemistry , physics , statistics , mathematics , oceanography , quantum mechanics , astronomy , geology , polymer
Accurate kinetic measurements of the rate constants for the acidolysis of five N ‐acetyl‐ N ‐(4‐methoxybenzyl)‐α,α‐trialkyl glycine cyclohexyl amides in TFA were performed at 25 °C and the reactions monitored by HPLC. In all cases the results were consistent with a first order behaviour with respect to the substrate. No direct correlation was obtained with these data between the rate constant values and structure, but a good correlation coefficient was obtained when a multiple regression analysis was applied by taking advantage of a Taft equation using appropriate polar and steric substituent parameters. In a plot of the values observed for log k against those calculated by this equation all five points fell very close to the line of perfect correlation. The calculated sensitivity coefficients to polar and steric contributions were used to discuss the experimental results and showed that the acidolysis were comparatively less affected by steric effects than expected. Copyright © 2005 European Peptide Society and John Wiley & Sons, Ltd.