Abstract

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 k₂₉₈ 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.

中文翻译：

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1,4-二恶烷水溶液中酪氨酰脯氨酸对苯甲酰化的反应性

摘要

在298-313 K的温度范围内研究了L-酪氨基-L-脯氨酸（Tyr-Pro）与苯甲酸二和三硝基苯酯（40％的水）的反应动力学。发现反应速率常数k ₂₉₈在0.035至0.564 L·mol ^–1 ·s ^–1的范围内变化，活化势垒从39 kJ / mol变为51 kJ / mol。通过DFT / B3LYP / cc-pVTZ方法模拟了二肽的中性和阴离子形式。对这些形式的电子密度分布的自然键轨道分析表明，二肽分子中优选的亲核中心是伯氨基的氮原子，而不是酚羟基的氧原子。