Amide Molecules With Guanine Interactions And Multi-channel Proton Transfer Reaction Theory

As one of the simplest and the most fundamental phenomena in the tautomeric equilibria and oxidation-reduction reactions,proton transfers paly an important role either in chemical or biochemical processes.Elements within and between proton transfer widespread elements in photosynthesis chain,respiratory chain,enzymatic catalysis response of the cell metabolism process,a driving force behind cell procedures and biological information to energy quantum coding and transmission model.Many studies have been performed on proton transfer reactions as its important role both in chemical and biological process.In this paper we study proton transfer reaction use the analysis of the vibrational model and the vibrational frequencies,and the theory of multi-channel reaction also be used in the study.In our study,we choose serinamide and guanine as the objections of our investigation.The useful DFT methods are used in the studies of multi-channel reaction of proton transfer and some important conclusions were drawn.The whole paper consists of five chapters.The first chapter is the preface and can be divided into four parts.The first part briefly introduces the history of the modern quantum chemistry theory.The second part narrates the multi-channel reaction of proton transfer processes.The third part introduces the peptide model.The fourth part introduces the main work and practical meanings of this paper.The second chapter introduces the related calculation methods which are used in this paper.In brief,the former two chapters are the basis and background of our studies,which offer us with useful and reliable quantum methods.On the basis of these theories,in Chapter three,for the purpose of investigating the Multi-channel reactions of intramolecular proton transfer(IPT)on serinamide in the ground state (GS)and excited state(ES),five pairs of mirror-image conformers in ES and eight ones in GS for serinamide are determined by(DFT)B3LYP method at 6-311 ++G^**level.And what's more, four different channels for IPT are confirmed by theoretical calculations for ES and GS, respectively.The most favourable channels of reaction are obtained in ES and GS.The active energies needed to the proton transfer reaction processes in ES and GS are compared with each other,and the conclusion is drawn that the IPT reaction processes in ES are much easier than those in GS.In Chapter four,the hydrogen bonding of complexes formed between formamide and guanine molecules are completely investigated using density functional theory(DFT)at 6-311++G(d,p) level,which makes a good basis for the further investigation of the influence of the peptide model on the IPT processes of DNA simple bases(such as guanine)in the living systems.Nine stable cyclic structures stabilified by two hydrogen bonds are found.One of them is a six-membered ring,five of them are seven-membered rings and the others are eight-membered rings.After the compare of the HBs of these complexes,the most and the last stable complexes are confirmed respectively.The infrared(IR)spectrum frequencies,IR intensities and vibrational frequency shifts are also reported.In Chapter five,on the basis of the conclusions drawn in Chapter four,the influence of the peptide model(formamide)on the IPT processes of DNA simple base guanine in the living systems has been studied at B3LYP/6-311++G(d,p)level.In the chapter,we take guanine monomer and five complexes(FG1,FG2,FG3,FG4 and FG5)as investigative objection and obtain the assisted and protected effects of formamide on IPT in guanine.What's more,the most favourable channel is found as well as the last favourable one.In respect that the objections we investigated are on the basis of the simulation of the biologic systems,the conclusions we obtained are of the essence for the research of biologic phenomena such as the cell metabolism process,the biological information transfer,DNA mutation,cell canceration.and so on.