Theoretical Studies On Activity Of The Nucleic Acid By The Environmental Small Molecules

When the organism is stimulated by the outside world,it will produce a large amount of reactive oxygen species,which will destroy the balance of oxidation and antioxidation in the organism,and then lead to the oxidative damage of nucleic acid,leading to the aging of life and the formation of some major diseases.Due to the worsening of environmental pollution,the influence of some small molecules in the environment on the nucleic acid activity in vivo has become an important topic that can not be ignored.In this paper,density functional theory and Gussian 2016 software were used to study the influence of environmental small molecules on nucleic acid reactivity.These two processes are both negative barrier and exothermic reactions,indicating that the structure of ethylene glycol and 5-hydroxy-5-methylcaprolactam are easy to form.The reaction path of the cis-isomer of thymine peroxide radical is similar to the trans-isomer.Because the reaction of forming thymine glycol is a significant negative barrier and exothermic process,it is easier to obtain the biomarker of glycol for the cis-isomer of thymine peroxide radical.At the same time,the difference of activation properties of C(sp³)-H between?-type C·and?-type C-OO·.The-CH₂group of propylene glycol was used as H donor,and a series of C·and C-OO·complexes which are similar to the thymine base were used as H receptors.The results show that C·has stronger oxidation activity for C-H bond from the point of view of structure and spatial position,while from the point of view of kinetics,C-OO·has more obvious advantage in activating C-H bond.At the level of M06-2X/6-31+G(d,p),the effects of NO and CO on the activity of uracil peroxy radical reaction were studied.It is found that the existence of electrons greatly reduces the reaction barrier(only 4.4 kcal/mol)of NO oxidation by peroxy radical,which is beneficial to the formation of NO₂.At the same time,the reaction pathways of hydroxyl activated uracil peroxy radical with NO and CO were investigated.By comparing the reaction process of NO and CO with uracil peroxy radical,it was found that the reaction path was basically the same,which eventually led to the formation of biomarker molecule ethylene glycol.