Kuritsyn, L. V.; Kalinina, N. V., Russian Journal of Organic Chemistry, 1994, vol. 30, # 5.2, p. 767 - 770
作者:Kuritsyn, L. V.、Kalinina, N. V.
DOI:——
日期:——
Reactivity of Tyrosyl–Proline toward Benzoylation in Aqueous
1,4-Dioxane
作者:T. P. Kustova、I. I. Lokteva、L. B. Kochetova、D. S. Khachatryan
DOI:10.1134/s1070428020060111
日期:2020.6
The kinetics of the reaction of L-tyrosyl-L-proline (Tyr-Pro) with di- and trinitrophenyl benzoates in aqueous 1,4-dioxane (40 wt % of water) were studied in the temperature range 298-313 K. The reaction rate constant k(298) was found to vary in the range from 0.035 to 0.564 L.mol(-1).s(-1), and the activation barrier changed from 39 to 51 kJ/mol. The neutral and anionic forms of the dipeptide were simulated by the DFT/B3LYP/cc-pVTZ method. Natural bond orbital analysis of the electron density distribution in these forms showed that the preferred nucleophilic center in the dipeptide molecule is the nitrogen atom of the primary amino group rather than the oxygen atom of the phenolic hydroxy group.
Effect of pH on the reactivity of dipeptides and α-amino acids in the N-acylation
作者:L. V. Kuritsyn、N. V. Kalinina、L. B. Kochetova
DOI:10.1134/s1070363212110126
日期:2012.11
The reaction kinetics of Gly, L-alpha-Ala, Gly-Gly, L-alpha-Ala-L-alpha-Ala and beta-Ala-beta-Ala with picryl benzoate in water (40 wt %)-2-propanol was investigated. At pH = 4-8 the rate constants of N-acylation of the anionic form of dipeptides are less than those of the corresponding amino acid anions, in agreement with their basicity, whereas the relative effective rate constants of reactions depend on pH: in acidic, neutral and slightly alkaline media the k (ef) values are higher for the dipeptides, and in a strongly alkaline medium, for the amino acids. These differences are due to the changes in the concentrations of reactive forms of amino acids and dipeptides in the system at varying the medium pH.