REACTIVE INTERMEDIATES IN PHOTOCHEMICAL REACTION OF BIOLOGICALLY RELEVANT PURINES

人体皮肤暴露在持续的紫外线阳光下会导致多种疾病 病理影响，如：晒伤、某些形式的皮肤癌、衰老 以及免疫系统的紊乱。在分子水平上，这些效应 已经用光致细胞核中的碱基损伤来解释 酸。有报道称，在紫外线照射下产生了嘌呤类光产物 这也可能导致这些有害的影响。稳定的产品 参与其中的脱氧核糖核酸或活性中间体的嘌呤部分 光化学过程还没有被详细研究。在这 延续建议我们的主要目标是： 1.继续研究和表征激发态和 活性中间体参与光化学和 嘌呤二核苷、寡核苷酸和苯二酚的光破坏反应 多核苷酸用作DNA模型化合物。这些将被描述为 从它们在激光下的吸收光谱和动力学行为 闪光光解技术。 2.研究嘌呤自由基阳离子与生物的反应 重要的分子，如氨基酸、糖和氧气使用激光 闪存技术。 3.确定和表征光破坏中的主要产品 嘌呤核苷、核苷酸和二核苷的作用机制 将这些产物与其短暂的中间前体相关联。 这些目标将通过执行量子产额测量来实现 并使用光谱分析技术。 4.确定参与光引发嘌呤反应的中间体 与被认为是侧链模型的分子的交联反应 氨基酸的链和与氨基酸的关系。

The exposure of human skin to continuous UV sunlight can cause a variety of pathological effects such as: sunburn, certain forms of skin cancer, aging and disorders in the immune system. At the molecular level these effects have been explained in terms of photoinduced base lesions in the nucleic acids. There have been reports of purine photoproducts in UV irradiated DNA which could also lead to these deleterious effects. Stable products of the purine moieties of DNA or reactive intermediates participating in these photochemical processes have not been studied in detail. In this continuation proposal our main objectives are to: 1. Continue with the study and characterization of excited states and reactive intermediates participating in the photochemical and photodestruction reactions of purine dinucleosides, oligo, and polynucleotides used as DNA model compounds. These will be characterized from their absorption spectra and kinetic behavior obtained with laser flash photolysis techniques. 2. Study the reactions of purine radical cations with biologically important molecules such as amino acids, sugars and with oxygen using laser flash techniques. 3. Identify and characterize the major products in the photodestruction mechanism of purine nucleosides, nucleotides and dinucleosides and correlate these products to their short lived intermediate precursors. These goals will be accomplished by performing quantum yield measurements and using spectroanalytical techniques. 4. Identify the intermediates participating in the purine photoinitiated cross-linking reactions with molecules considered to be models for the side chains of amino acids and with the amino acids.