REACTIVE INTERMEDIATES IN PHOTOCEMICAL REACTIONS OF BIOLOGICALLY RELEVANT PURINES

紫外线辐射会对DNA造成不同类型的损伤 如果不加以修复，可能会导致致命、突变和致癌 效果。在过去的十年里，有报道称 紫外光照射下DNA中嘌呤光产物的形成 导致有害的影响。单体的光化学研究 我们实验室的嘌呤及其衍生物表明 光破坏的产率与单体的观察到的结果一样高 嘧啶类化合物。此外，高活性中间体的形成 已经被观察到了。这些可能会引发与其他碱基的反应 和/或接近DNA的分子。我们的主要目标是： 1.研究和表征激发态和反应态 参与光破坏的中间体和 嘌呤脱氧核苷酸二聚体、寡聚和二聚体的光化学反应 多核苷酸。这些将通过它们的吸收来表征 激光和常规激光获得的光谱和动力学行为 闪光光解和荧光光谱分析。这些研究将 提供有关新近形成的 在DNA中观察到嘌呤光产物。 2.确定光解过程中的稳定产物 脱氧鸟苷和脱氧鸟苷一磷酸及其酶的建立 光破坏机制。 3.确定参与嘌呤的中间体 有机化合物的光引发交联化反应 被认为是氨基酸侧链的模型。 将获得的信息将有助于了解 紫外线对生命系统的有害影响，如 突变、衰老和致癌。

Ultraviolet radiation produces different types of lesions on DNA which unrepaired could lead to lethal, mutagenic and tumorigenic effects. In the last decade there have been reports on the formation of purine photoproducts in UV irradiated DNA which could lead to deleterious effects. Photochemical studies on monomeric purines and their derivatives from our laboratory indicate photodestruction yields as high as the one observed for monomeric pyrimidines. Also, the formation of highly reactive intermediates have been observed. These could initiate reaction with other bases and/or molecules close to the DNA. Our main objectives are: 1. To study and characterize the excited states and reactive intermediates participating in the photodestruction and photochemical reactions of purine deoxynucleotide dimers, oligo and polynucleotides. These will be characterized from their absorption spectra and kinetic behavior obtained with laser and conventional flash photolysis and fluorescence spectrometry. These studies will provide information on the mechanism of formation of the recently observed purine photoproducts in DNA. 2. Identify the stable products in the photodestruction of deoxyguanosine and deoxyguanosine monophosphate and establish its photodestruction mechanism. 3. Identify the intermediates participating in purine photoinitiated cross linking reactions with organic compounds considered to be models for the side chain of amino acids. The information to be obtained will aid in the understanding of the detrimental effects of UV light on living systems such as mutations, aging and carcinogenesis.