Studies on N4-(2-deoxy-D-pentofuranosyl)-4,6-diamino-5-formamidopyrimidine (Fapy•dA) and N6-(2-deoxy-D-pentofuranosyl)-6-diamino-5-formamido-4-hydroxypyrimidine (Fapy•dG)
Studies on N4-(2-deoxy-D-pentofuranosyl)-4,6-diamino-5-formamidopyrimidine (Fapy•dA) and N6-(2-deoxy-D-pentofuranosyl)-6-diamino-5-formamido-4-hydroxypyrimidine (Fapy•dG)
复制标题
DOI：
10.1021/bi011490q
复制
发表时间：
2001-12-25
期刊：
影响因子：
2.9
通讯作者：
Rithner, CD
中科院分区：
文献类型：
--
作者：
Greenberg, MM;Hantosi, Z;Rithner, CD
DNA 暴露于氧化应激会产生多种 DNA 损伤，包括源自嘌呤的甲酰胺嘧啶。这些病变可能在致癌过程中发挥重要作用。我们首次化学合成了单体形式的 Fapy.dA (1) 以及在指定位点包含该病变或 Fapy.dG 的寡核苷酸。单体 Fapy.dA 在 25°C 的磷酸盐缓冲液（pH 7.5）中容易差向异构化。 β-端基异构体的比例为 1.33:1.0，并且在不到 7 小时内达到平衡。 Fapy.dA 单体中的去糖基化在 37 至 90°C 范围内遵循一级动力学。在共同温度（55℃）下测量单体和寡核苷酸底物中 Fapy.dA 去糖基化的速率常数，发现在实验误差内（t（1/2）= 20.5 h）是相同的。对 I 去糖基化测量的激活参数的实施表明，Fapy.dA 在 37°C 去糖基化的半衰期约为 103 小时。对寡核苷酸中 Fapy.dG 去糖基化的速率常数的分析表明，该损伤在 55℃ 下的水解耐受性比 Fapy.dA 高 25 倍。这些结果表明 Fapy.dA 和 Fapy.dG 在 DNA 中的寿命足够长，因此有必要研究它们的遗传毒性，并且两种异头物都将在这段时间内存在。
Exposure of DNA to oxidative stress produces a variety of DNA lesions including the formamidopyrimidines, which are derived from the purines. These lesions may play important roles in carcinogenesis. We achieved the first chemical syntheses of a monomeric form of Fapy.dA (1) and oligonucleotides containing this lesion or Fapy.dG at a defined site. Monomeric Fapy.dA readily epimerized at 25degreesC in phosphate buffer (pH 7.5). The beta-anomer was favored by a ratio of 1.33:1.0, and equilibration was achieved in less than 7 h. Deglycosylation of Fapy.dA in the monomer follows first-order kinetics from 37 to 90.C. The rate constants for deglycosylation of Fapy.dA in the monomeric and oligonucleotide substrates were measured at a common temperature (55degreesC) and found to be the same within experimental error (t(1/2) = 20.5 h). Implementation of the activation parameters measured for the deglycosylation of I indicates that the half-life for deglycosylation of Fapy.dA at 37degreesC is approximately 103 h. Analysis of the rate constant for deglycosylation of Fapy.dG in an oligonucleotide, revealed that this lesion is similar to25 times more resistant to hydrolysis than Fapy.dA at 55degreesC. These results indicate that Fapy.dA and Fapy.dG will be sufficiently long-lived in DNA so as to warrant investigation of their genotoxicity, and both anomers will be present during this time.