ELECTRON TRANSFER IN MICRO-HETEROGENEOUS MEDIA

这项建议的主要目标是研究模型和 真实的生物环境对早期化学反应的影响 在电离能量的沉积过程中产生的物种 (2)涉及其他损害健康的情况。这个 所讨论的化学物种是自由基，反应如下 其中发生了单电子转移。新知识将会有 理解辐射诱发机制的广泛意义 被认为与自由基有关的损伤和其他健康问题 前体或中间体。迄今为止对电子转移的研究最多 动力学已经在理想化的均匀相中进行，而且 信息已经积累起来了。然而，在关系最密切的媒体中 与生物病例密切相关，因为生物病例是复杂的、分割的和 微异质性，尝试的工作很少；以及 这些因素几乎是未知的。这里设想的工作试图 解决这一地区的问题。重点将放在描述中的方式 哪些分隔的聚集体和界面区域会影响 自由基间电子转移的动力学和平衡问题 物种。待研究的体系类型包括 水(胶束)、反胶束、微乳、囊泡、脂质体、 细胞幽灵和膜碎片。氧化还原衬底将包括 喹酮、黄素、紫精、氧气、细胞色素、有机杂环、 金属络合物和硝基芳香族物种。除了调查 在分离的单个分子之间的转移，该程序还包含 研究含有供体-受体对的单分子，其中供体-受体对由一个 间隔器框架。这最后一个方面是新的，并提供了一个令人兴奋的 电子转移反应研究的另一种方法 微非均质介质。将使用的实验方法包括电子 脉冲辐解与纳秒动力学分光光度联用 分辨率为10-11秒的激光闪光光谱分析。 双分子速率常数、分子内速率、平衡常数和 热力学参数将被测量。与健康相关的 这个节目关系到我们对高能危害的理解。 辐射，我们通过改善肿瘤治疗方法的能力 放射治疗，以及免费的基本方面的知识 激进的生物学。

This proposal has as its main objective a study of the effects of model and real biological environments upon the reactions of the early chemical species produced (i) during the deposition of energy from ionizing radiations and (ii) involved in other health damaging situations. The chemical species in question are free radicals, and the reactions are those in which single electron transfers occur. The new knowledge will have extensive significance in understanding the mechanisms of radiation-induced lesions and other health problems that are thought to involve free radical precursors or intermediates. Most research to date in electron transfer kinetics has been performed in idealized homogeneous phases, and much information has been accumulated. However, in media that relate most closely to the biological case which is complex, compartmentalized and microheterogeneous, very little work has been attempted; and the effects of such factors are virtually unknown. The work envisaged here attempts to address this area. Emphasis will be placed on characterizing the ways in which compartmentalized aggregates and interfacial regions influence the kinetic and equilibrium aspects of electron transfer between free radical species. Types of systems to be studied include surfactant assemblies in water (micelles), reverse micelles, micro-emulsions, vesicles, liposomes, cell ghosts and membrane fragments. Redox substrates will include quinones, flavins, viologens, oxygen, cytochromes, organic heterocycles, metal complexes and nitro-aromatic species. In addition to investigating transfers between separated individual molecules, the program also contains work on single molecules that contain a donor-acceptor pair separated by a spacer framework. This last aspect is new and offers an exciting alternative approach to the study of electron transfer reactions in microheterogeneous media. Experimental methods to be used include electron pulse radiolysis coupled to kinetic spectrophotometry with nanosecond time resolution and laser flash spectrography with 10-11 second resolution. Bimolecular rate constants, intramolecular rates, equilibrium constants and thermodynamic parameters are to be measured. The health-relatedness of this program concerns our understanding of the hazards of high energy radiation, our capabilities for improving ways of tumor therapy by radiation treatment, and a knowledge of the fundamental aspects of free radical biology.