CAJ | 학술논문

应用量子化学方法对2,6-二氨基-4-羟基-5-甲酰胺嘧啶( Fapy-G)与正常碱基作用形成的20种氧化碱基对的多种性质进行了理论分析,碱基G的C8位被氧化后N7和N9位分别增加一个H原子,使其由氢键受体变成氢键供体, N7, N9及O6原子所带的电荷变负,同时O6作为氢键受体的能力增强.与碱基单体相比,碱基对中形成氢键的受体原子所带的电荷平均减小0.05 e；供体H原子所带的电荷平均增大0.02 e. Fapy-G分子中六元环上受体N原子参与形成氢键时,环的呼吸振动模式和N与对位C的振动模式的振动频率蓝移；与氢键相关的振动频率红移.所有氧化碱基对中, NH…N比NH…O氢键作用更强,且在NH…N氢键中,在六元环上的供体N原子形成的氢键比在氨基或开环上的供体N原子形成的氢键强. Fapy-G与碱基A作用结合能区域顺序为1>2>4>3,与碱基T(R)作用区域顺序为3=4>1>2；水溶液使Fapy-G与碱基C作用的结合能减弱程度最大,结合能达到41.84~58.58 kJ/mol,且使碱基对结合能力次序发生改变.
응용양자화학방법대2,6-이안기-4-간기-5-갑선알밀정( Fapy-G)여정상감기작용형성적20충양화감기대적다충성질진행료이론분석,감기G적C8위피양화후N7화N9위분별증가일개H원자,사기유경건수체변성경건공체, N7, N9급O6원자소대적전하변부,동시O6작위경건수체적능력증강.여감기단체상비,감기대중형성경건적수체원자소대적전하평균감소0.05 e；공체H원자소대적전하평균증대0.02 e. Fapy-G분자중륙원배상수체N원자삼여형성경건시,배적호흡진동모식화N여대위C적진동모식적진동빈솔람이；여경건상관적진동빈솔홍이.소유양화감기대중, NH…N비NH…O경건작용경강,차재NH…N경건중,재륙원배상적공체N원자형성적경건비재안기혹개배상적공체N원자형성적경건강. Fapy-G여감기A작용결합능구역순서위1>2>4>3,여감기T(R)작용구역순서위3=4>1>2；수용액사Fapy-G여감기C작용적결합능감약정도최대,결합능체도41.84~58.58 kJ/mol,차사감기대결합능력차서발생개변.
One of the primary oxidative DNA damage is 2,6-diamino-4-hydroxy-5-formamido pyrimidine, named Fapy-guanine(Fapy-G), which is the product of guanine oxidized at C8. The properties of 20 oxidative base pairs which contains Fapy-G were investigated via quantum chemistry methods. All model molecular structures were optimized with B3 LYP/6-31+G* method and the frequency calculations were carried out to confirm that all the structures obtains were geometrically stable. The energies were determined at the MP2/aug-cc-pVDZ level with BSSE corrections. The calculation results show that N7, N9 became hydrogen bond donor from accepter. Natural atomic charge of N7, N9 and O6 get more negative. The ability of O6 as H-bond donor enhanced. The bond lengths of C5—N7 and N7—C8 were increased by 0. 0045 and 0. 0063 nm, C4—N9 was decreased by 0. 0015 nm. Compared with bases monomers, natural atomic charge of proton acceptors in hydrogen bond complexes increased by 0. 05 e averagely, which is 8% of the original charge;natural atomic charges for proton donors have a decrease of 0. 02 e, which is 4% of the original charge. Com-pared with Fapy-G, when the N atom in Fapy-G six-membered ring was formed H-bond, the ring breathing and N-para-C vibrational frequencies were blue shifts. The vibrational frequencies were related to H-bond red shifts in all the base pairs. NH…N is stronger than NH…O in all the base pairs and in NH…N the hydrogen bond energy of donor N atom in six-membered ring are bigger than donor N atom in NH2 or open-ring. When Fapy-G pairs with base A, the binding energy region order is 1>2>4>3. When Fapy-G pairs with base T(R), the binding energy region order is 3=4>1>2. In water solvent, the binding energies of Fapy-G pairs with base C reduced to 41. 84—58. 58 kJ/mol, and the order of the binding energy was changed.