ELECTRON TRANSFER IN MICRO-HETEROGENEOUS MEDIA

这项建议的主要目的是研究模型的影响， 真实的生物环境对早期化学反应的影响 （i）电离产生的能量沉积过程中产生的物质 （ii）涉及其他损害健康的情况。 的 化学物种的问题是自由基，和反应是那些 其中发生单电子转移。 新的知识将会 对理解辐射诱发的机制具有广泛的意义 病变和其他健康问题，被认为涉及自由基 前体或中间体。 迄今为止在电子转移方面的大多数研究 动力学已经在理想化的均相中进行，并且 信息已经积累。 然而，在与大多数媒体 与复杂的生物学案例密切相关， 微观异质，很少的工作已经尝试;和影响 这些因素实际上是未知的。 这里设想的工作试图 解决这个领域。 重点将放在表征的方式， 分隔的聚集体和界面区域影响 自由基间电子转移动力学和平衡 物种 待研究的系统类型包括表面活性剂组件， 水（胶束），反胶束，微乳液，囊泡，脂质体， 细胞幽灵和膜碎片。 氧化还原底物将包括 醌，黄素，紫精，氧，细胞色素，有机杂环， 金属络合物和硝基芳族物质。 除了调查 在分离的单个分子之间转移，该程序还包含 工作的单分子，包含一个供体受体对分离的 间隔物框架。 这最后一个方面是新的，并提供了一个令人兴奋的 研究电子转移反应的另一种方法， 微非均匀介质 使用的实验方法包括电子 纳秒脉冲辐解动力学光度法 分辨率和10 - 11秒分辨率的激光闪光光谱法。 双分子速率常数、分子内速率、平衡常数和 需要测量热力学参数。 健康相关性 这个项目涉及到我们对高能辐射危害的理解 放射，我们改善肿瘤治疗方法的能力， 辐射治疗，以及免费的基本方面的知识 激进生物学

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.