【摘要】 本文研究了脱氧胸腺嘧啶核苷酸（dTMP）辐射释磷的机理以及组氨酸对dTMP释磷的保护作用。dTMP辐射损伤释放出无机磷主要是由于水辐解产生的OH自由基在C4’位置发生抽氢反应所致。实验求得这一反应的速率常数为（1.7±0.1）×10⁸M^-1S^-1,同时求得OH自由基与dTMP大分子的反应速率常数为（5.0±0.2）×10⁹M^-1S^-1 由于组氨酸能有效地清除OH自由基,因而组氨酸对dTMP释磷的保护作用是显著的。从辐照后测得DNA溶液粘度变化的结果来看,组氨酸对DNA变性——降解作用也呈现出明显的保护作用。更多还原

【Abstract】 The mechamism of releasing inorganic phosphate from Deoxythymi-dine-5′-monophosphate（dTMP） and radiation protection on releasing inorganic phosphatfrom dTMP by Histidine have been inverstigated.The release of inorganic phosphate fromdTMP results ma finly from the acting of OH radical with H atom at position C₄^′.It wascalculated that rate constant for reaction of OH radical with position C₄^′is （1.7±0.1）×10⁸M^-1S^-1 and the rate constant for reaction of OH radical with dTMP is （5.0±0.2）×10⁹M^-1S^-1. Because the OH radical was scavenged by Histidine effectively, the radiation protec-tion from releasing inorganic phosphate from dTMP by Histidine was obvious. It may beseen from viscosity change of DNA after irradiation that Histidine exhibits marked pro-tection from denaturation and degradation of DNA.更多还原