ELECTRON TRANSFER IN MICRO-HETEROGENEOUS MEDIA

微异质介质中的电子传输

• 批准号: 3279742
• 负责人: MICHAEL A RODGERS
• 金额: $ 9.88万
• 依托单位: BOWLING GREEN STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-07-01 至 1989-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3279742
• 关键词: cytochromes; electron transport; emulsions; erythrocyte membrane; flavins; free radicals; heterocyclic compounds; ionizing radiation; laser spectrometry; liposomes; mathematical model; metal complex; micelles; neoplasm /cancer radiation therapy; nitrogen compounds; oxidation reduction reaction; polymers; pyridine; quinones; radiation hazard; radiobiology; relative biological effectiveness; respiratory oxygen; thermodynamics

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.

该提案的主要目标是研究模型和 早期化学反应的真实生物环境 (i) 电离能量沉积过程中产生的物质 辐射和 (ii) 参与其他损害健康的情况。 这 所讨论的化学物质是自由基，其反应是 其中发生单电子转移。 新的知识将会有 对于理解辐射诱发的机制具有广泛意义 病变和其他被认为与自由基有关的健康问题 前体或中间体。 迄今为止大多数电子转移研究 动力学已在理想化的均相中进行，并且许多 信息已经积累。 然而，在最相关的媒体中 与生物案例密切相关，其复杂性、分区性和 微观异质性，尝试的工作很少；和影响 这些因素实际上是未知的。 这里设想的工作试图 解决这个区域的问题。 重点将放在描述方法的特征上 哪些分隔的聚集体和界面区域影响 自由基之间电子转移的动力学和平衡方面 物种。 要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、 细胞鬼影和膜碎片。 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香族物质。 除了调查之外 在分离的单个分子之间进行转移，该程序还包含 研究包含供体-受体对的单个分子，该对由 间隔框架。 最后一个方面是新的，并提供了令人兴奋的 研究电子转移反应的另一种方法 微观异质介质。 所使用的实验方法包括电子 脉冲辐射分解与纳秒时间动力学分光光度法耦合 分辨率和激光闪光光谱法具有 10-11 秒的分辨率。 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 该计划涉及我们对高能危害的理解 辐射，我们改善肿瘤治疗方法的能力 放射治疗，以及免费基本方面的知识 激进生物学。