Double-Base Lesions Are Produced in DNA by Free Radicals

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• 作者：Maccubbin ; Alexander E. ; Iijima ; Herbert ; Ersing ; Noreen ; Dawidzik ; Jean B. ; Patrzyc ; Helen B. ; et. al.
• 刊名：Archives of Biochemistry and Biophysics
• 出版年：2000
• 出版时间：March 1, 2000
• 年：2000
• 卷：375
• 期：1
• 页码：119-123
• 全文大小：75.8 K

文摘

Evidence has been accumulating at the oligomer level that free radical-initiated DNA damage includes lesions in which two adjacent bases are both modified. Prominent examples are lesions in which a pyrimidine base is degraded to a formamido remnant and an adjacent guanine base is oxidized. An assay has been devised to detect double-base lesions based on the fact that the phosphoester bond 3′ to a nuclesoside bearing the formamido lesion is resistant to hydrolysis by nuclease P1. The residual modified dinucleoside monophosphates obtained from a nuclease P1 (plus acid phosphatase) digest of DNA can be ³²P-postlabeled using T4 polynucleotide kinase. Using this assay the formamido single lesion and the formamido–8-oxoguanine double lesion were detected in calf thymus DNA after X-irradiation in oxygenated aqueous solution. The lesions were measured in the forms d(P^FpG) and d(P^FpG^H), where P^F stands for a pyrimidine nucleoside having the base degraded to a formamido remnant and G^H stands for 8-oxo-deoxyguanosine. The yields in calf thymus DNA irradiated 60 Gy were 8.6 and 3.2 pmol/μg DNA, respectively.