REACTIVE INTERMEDIATES IN PHOTOCEMICAL REACTIONS OF BIOLOGICALLY RELEVANT PURINES

紫外线辐射对DNA产生不同类型的损伤 如果不修复，可能会导致致命的，致突变的和致肿瘤的 方面的影响. 在过去的十年里，有报道称， 在紫外线照射的DNA中形成嘌呤光产物， 导致有害影响。 单体的光化学研究 嘌呤及其衍生物表明， 光破坏产率与单体 嘧啶。 此外，高活性中间体的形成 已经被观察到了。 这些可以引发与其他碱的反应 和/或接近DNA的分子。 我们的主要目标是： 1. 为了研究和表征激发态和反应性 参与光破坏的中间体， 嘌呤脱氧核苷酸二聚体、寡聚体和 多核苷酸。 这些将从它们的吸收特性 光谱和动力学行为获得激光和常规 闪光光解和荧光光谱法。 这些研究将 提供关于最近 观察到DNA中的嘌呤光产物。 2. 确定光破坏中的稳定产物 脱氧鸟苷和脱氧鸟苷一磷酸，并建立其 光破坏机制 3. 识别参与嘌呤的中间体 与有机化合物的光引发交联反应 被认为是氨基酸侧链的模型。 获得的信息将有助于理解 紫外线对生命系统的有害影响， 突变、衰老和致癌作用。

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.