Thymine fragment damage retained in the DNA polynucleotide chain after gamma irradiation in aerated solutions. II.
Thymine fragment damage retained in the DNA polynucleotide chain after gamma irradiation in aerated solutions. II.
复制标题
在充气溶液中进行伽马射线照射后，胸腺嘧啶片段损伤保留在 DNA 多核苷酸链中。
作者：
R. Teoule;C. Bert;A. Bonicel
胸腺嘧啶片段的化学修饰是通过水解法确定的，这是由于DNA的充气溶液受到伽马照射而导致的，这些溶液仍然与多核苷酸链相连。甲酸在90/sup 0/C下进行水解，通过N-糖苷键的断裂，顺式和反式-5，6-二羟基-5，6-二氢胸腺嘧啶(1和2)、5-羟基-5-甲基海因(3)、甲酰基脲(4)和尿素(5)从DNA链主干上释放出来。这些缺陷通过层析和微量反应得到了明确的表征。这些水解条件使得能够测量由多核苷酸链承担的主要缺陷1、2、(总和)和3的数量。利用在辐射过程中一氧化碳和丙酮酰胺直接从链上释放的事实，证明了N-甲酰胺脱氧核糖DNA缺陷的形成(6)。提出了1-5和6-丙酮酰胺和一氧化碳缺陷的形成机理。
The chemical modifications of the thymine fragment due to gamma irradiation of aerated solutions of DNA, which remain linked to the polynucleotide chain, were determined by hydrolysis. The formic acid hydrolysis was carried out at 90/sup 0/C and in this way cis- and trans-5,6-dihydroxy-5,6-dihydrothymine (1 and 2), 5-hydroxy-5-methylhydantoin (3), formylurea (4), and urea (5) were released from the DNA chain backbone by rupture of the N-glycosidic bond. These defects were characterized unambiguously by chromatography and microreactions. These hydrolysis conditions made it possible to measure the quantities of the main defects 1,2, (sum) and 3 which were borne by the polynucleotide chain. By taking advantage of the fact that carbonic oxide and pyruvamide were released directly from the chain during the irradiation the formation of the N-formamidodeoxyribose DNA defect (6) was demonstrated. A mechanism to explain the formation of these defects, 1 to 5 and 6, pyruvamide and carbonic oxide, is suggested.