Novosjolova Irina, Kennedy Scott D, Rozners Eriks
Department of Chemistry, Binghamton University, The State University of New York, Binghamton, NY, 13902, USA.
Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, NY, 14642, USA.
Chembiochem. 2017 Nov 2;18(21):2165-2170. doi: 10.1002/cbic.201700400. Epub 2017 Sep 26.
The development of nucleic acid base-pair analogues that use new modes of molecular recognition is important both for fundamental research and practical applications. The goal of this study was to evaluate 2-methoxypyridine as a cationic thymidine mimic in the A-T base pair. The hypothesis was that including protonation in the Watson-Crick base pairing scheme would enhance the thermal stability of the DNA double helix without compromising the sequence selectivity. DNA and peptide nucleic acid (PNA) sequences containing the new 2-methoxypyridine nucleobase (P) were synthesized and studied by using UV thermal melting and NMR spectroscopy. Introduction of P nucleobase caused a loss of thermal stability of ≈10 °C in DNA-DNA duplexes and ≈20 °C in PNA-DNA duplexes over a range of mildly acidic to neutral pH. Despite the decrease in thermal stability, the NMR structural studies showed that P-A formed the expected protonated base pair at pH 4.3. Our study demonstrates the feasibility of cationic unnatural base pairs; however, future optimization of such analogues will be required.
开发利用新分子识别模式的核酸碱基对类似物对于基础研究和实际应用都很重要。本研究的目的是评估2-甲氧基吡啶作为A-T碱基对中阳离子胸腺嘧啶类似物的性能。其假设是，在沃森-克里克碱基配对方案中引入质子化将增强DNA双螺旋的热稳定性，同时不影响序列选择性。通过紫外热变性和核磁共振光谱法，合成并研究了含有新型2-甲氧基吡啶核碱基（P）的DNA和肽核酸（PNA）序列。在轻度酸性至中性pH范围内，P核碱基的引入导致DNA-DNA双链体的热稳定性损失约10°C，PNA-DNA双链体的热稳定性损失约20°C。尽管热稳定性有所下降，但核磁共振结构研究表明，在pH 4.3时，P-A形成了预期的质子化碱基对。我们的研究证明了阳离子非天然碱基对的可行性；然而，未来需要对这类类似物进行优化。
