核酸碱基互变异构体的结构、稳定性及其物理化学性质

核酸碱基是DNA及RNA分子的重要组成部分, 在基因遗传信息的传递方面起着主导作用. 核酸碱基存在多种互变异构体, 它们在DNA及RNA分子中主要以最稳定的异构体形式存在, 但是在气相或凝聚相中也有少量的其他异构体形式存在. 核酸碱基的稀有互变异构体往往能够引起碱基对的错配对, 这可能会导致DNA及RNA分子形成不规则的结构, 并进一步导致DNA或RNA双螺旋的自发突变. 因此, 对核酸碱基的互变异构体进行系统的研究, 有助于人们深入认识DNA和RNA分子的结构和性质. 国际上有很多研究小组已经通过实验和理论对核酸碱基互变异构体的结构、相对能量及其性质进行了研究. 本文对文献中有关核酸碱基互变异构体的实验和理论研究进行了综述. 在对前人研究进行归纳总结的基础上, 我们利用密度泛函计算对核酸碱基的互变异构体进行了排序, 得到的最优异构体结构参数和相对能量与实验值相比较为一致. 此外, 因为核酸碱基的物理化学性质可以为生物、化学、材料等方面的研究提供重要的基础性信息, 因此我们还对它们的电子亲和能、电离能、质子亲和能等研究进行了总结.

Structures,Stabilities and Physicochemical Properties of Nucleobase Tautomers

Nucleobases in DNA and RNA are important building blocks of the genetic codes and are critical in transferring genetic information. In general, nucleobases have many tautomers; but in DNA and RNA molecules they are mainly presented in the most stable forms. Uncommon tautomers can cause mispairing of base pairs to form irregular structures of DNA and RNA that lead to spontaneous mutations during replication. Thus, systematic studies of nucleobase tautomers are very important in understanding the structures and the characteristics of DNA and RNA. This review summarizes the experimental and theoretical studies in the literature and our density functional calculations on all the nucleobase tautomers. The relative energies of nucleobase tautomers and the structures of their lowest-energy tautomers fromour calculations are in good agreement with the experimental values in the literature. In addition, we also summarize the information of electron affinities, ionization potentials, and proton affinities of nucleobases reported in the literature.