ELECTRON TRANSFER REACTIONS IN MICRO-HETEROGENEOUS MEDIA

微异质介质中的电子转移反应

• 批准号: 3279740
• 负责人: MICHAEL A RODGERS
• 金额: $ 7.72万
• 依托单位: UNIVERSITY OF TEXAS AT AUSTIN
• 依托单位国家: 美国
• 财政年份: 1983
• 资助国家: 美国
• 起止时间: 1983-03-01 至 1986-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3279740
• 关键词: chemical aggregate; computer simulation; cytochromes; electron probe spectrometry; electron transport; emulsions; environmental contamination; erythrocyte membrane; flavins; free radicals; heterocyclic compounds; ionizing radiation; liposomes; mathematical model; metal complex; micelles; neoplasm /cancer radiation therapy; nitrogen compounds; oxidation reduction reaction; quinones; radiobiology; radiosensitizer; relative biological effectiveness

The proposed work is an experimental investigation of the quantitative effects of micro-heterogeneous environments upon the reactions of early chemical intermediates arising from the deposition of energy from ionizing radiation. The type of reaction to be studied is one electron transfer which is of major importance in radiation biological situations owing to the oxidizing and reducing abilities of the initially-formed reactive entities. Such reactions have been well-studied in homogeneous phases and their characteristics well-documented. Micro-heterogeneous media and their effects, however, have been largely ignored, thus creating a wide gap in current knowledge. This gap is particularly important in that a relevant data base for a full understanding of the molecular mechanisms of biological damage by ionizing radiation is not available. In this work, emphasis will be placed on characterizing the ways in which compartmentalized aggregates and interfacial regions influence the kinetic and equilibrium aspects of one-electron transfers between free radical species. Types of aggregates to be investigated include micelles, reverse micelles, micro-emulsions, vesicles, liposomes and membrane fragments. Redox substrates will include quinones, flavins, cytochromes, oxygen, heterocyclics, metal complexes and nitro-aromatic materials. The experimental methods will be almost exclusively the use of computer-assisted electron pulse radiolysis coupled to kinetic--spectrophotometry. Bimolecular rate constants, equilibrium constants, free energy and enthalpy determinations will be made. The long term objectives concern quantification of influences of biologically relevant media on chemical reactions which are of fundamental importance in radiation damage to tissue. This will have significance for (i) our understanding and control of the health hazards of high energy radiations, and (ii) our capabilities for developing and improving ways of tumor treatment by radiation therapy.

提出的工作是一项定量的实验研究。 微非均相环境对早期反应的影响 电离能量沉积产生的化学中间体 辐射。要研究的反应类型是单电子转移 这在辐射生物情况下非常重要，因为 初始生成的反应物的氧化还原能力 实体。这种反应在均相中已经得到了很好的研究，并且 他们的特征被很好地记录下来。微观非均质介质及其研究进展 然而，影响在很大程度上被忽视了，因此在 当前的知识。这一差距尤其重要，因为与 全面了解分子机制的数据库 电离辐射造成的生物损害是不可用的。在这部作品中， 重点将放在描述以下方式的特征上 分区化的聚集体和界面区影响动力学 和自由基间单电子转移的平衡问题 物种。要调查的聚集体类型包括胶束、反向 胶束、微乳、囊泡、脂质体和膜碎片。 氧化还原底物将包括醌、黄素、细胞色素、氧、 杂环化合物、金属络合物和硝基芳香族材料。这个 实验方法将几乎完全用于 计算机辅助电子脉冲辐解耦合到 动力学--分光光度法。双分子速率常数，平衡 将测定常量、自由能和热焓。《长河》 学期目标涉及生物影响的量化。 有关化学反应的相关媒体，这些化学反应在 对组织的辐射损伤。这将对(I)我们的 了解和控制高能辐射对健康的危害， 以及(Ii)我们开发和改进肿瘤治疗方法的能力 通过放射疗法进行治疗。