Abstract：
DNA exhibits remarkable charge transfer ability, which is crucial for its biological functions and potential electronic applications. The charge transfer process in DNA is widely recognized as primarily mediated by guanine, while the contribution of other nucleobases is negligible. Using the tight-binding models in conjunction with first-principles calculations, we investigated the charge transfer behavior of homogeneous GC and AT pairs. We found that the charge transfer rate of adenine significantly changes. With overstretching, the charge transfer rate of adenine can even surpass that of guanine, by as much as five orders of magnitude at a twist angle of around 26°. Further analysis reveals that it is attributed to the turnover of the relative coupling strength between homogeneous GC and AT base pairs, which is caused by the symmetry exchange between the two highest occupied molecular orbitals of base pairs occurring at different twist angles. Given the high degree of flexibility of DNA in vivo and in vitro conditions, these findings prompt us to reconsider the mechanism of biological functions concerning the charge transfer in DNA molecules and further open the potential of DNA as a biomaterial for electronic applications.
摘要：
DNA表现出显著的电荷转移能力，这对其生物功能和潜在的电子应用至关重要。DNA中的电荷转移过程被广泛认为主要由鸟嘌呤介导，而其他核碱基的贡献可以忽略不计。结合第一原理计算使用紧密结合模型，我们研究了均相GC和AT对的电荷转移行为。我们发现腺嘌呤的电荷转移速率显着变化。随着过度拉伸，腺嘌呤的电荷转移速率甚至可以超过鸟嘌呤，在大约26°的扭曲角下多达五个数量级。进一步的分析表明，这归因于均质GC和AT碱基对之间的相对耦合强度的周转，这是由在不同扭转角下发生的碱基对的两个最高占据分子轨道之间的对称交换引起的。鉴于DNA在体内和体外条件下的高度灵活性，这些发现促使我们重新考虑有关DNA分子电荷转移的生物学功能机制，并进一步打开DNA作为电子应用生物材料的潜力。
