BASE-PAIRING AND MUTAGENESIS - OBSERVATION OF A PROTONATED BASE PAIR BETWEEN 2-AMINOPURINE AND CYTOSINE IN AN OLIGONUCLEOTIDE BY PROTON NMR
BASE-PAIRING AND MUTAGENESIS - OBSERVATION OF A PROTONATED BASE PAIR BETWEEN 2-AMINOPURINE AND CYTOSINE IN AN OLIGONUCLEOTIDE BY PROTON NMR
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DOI：
10.1073/pnas.83.15.5434
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发表时间：
1986-08-01
影响因子：
11.1
通讯作者：
GOODMAN, MF
中科院分区：
文献类型：
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作者：
SOWERS, LC;FAZAKERLEY, GV;GOODMAN, MF
2 - 氨基嘌呤（AP）是一种强效的诱变碱基类似物，最常与胸腺嘧啶配对。在AP·T碱基对中，两个碱基都采用正常的互变异构形式。其诱变活性的机制源于它被观察到与胞嘧啶配对，这被归因于其更易采用罕见的亚氨基互变异构形式的倾向增强。在水中对含有AP·T碱基对的寡核苷酸双链中所有可交换质子进行的核磁共振研究显示出沃森 - 克里克氢键。当双链中的胸腺嘧啶被胞嘧啶取代时，我们观察到一个AP·C碱基对。可以看到AP的两个氨基质子，排除了罕见的互变异构形式。尽管可能存在几种替代结构，但研究表明第二个氢键是由AP·C碱基对的质子化形成的，并且这是生理条件下的主要形式。
2-Aminopurine (AP), a potent mutagenic base analogue, most frequently pairs with thymine. In the AP .cntdot. T base pair, both bases adopt normal tautomeric forms. The mechanism for the mutagenic activity arises from its observed pairing with cytosine, which has been ascribed to an enhanced tendency to adopt the rare imino tautomeric form. NMR studies in H2O on all the exchangeable protons in an oligonucleotide duplex containing an AP .cntdot. T base pair show Watson-Crick hydrogen bonding. When the thymine is replaced by cytosine in the duplex, we observe an AP .cntdot. C base pair. Both amino protons of AP are seen excluding the rare tautomeric form. Although several alternative structures are possible, it is shown that the second hydrogen bond is formed by protonation of the AP .cntdot.C base pair and that this is the dominant species under physiological conditions.