Photochemical reaction dynamics studies of nucleic acids

Abstract

Nucleic acids are the most important biomolecules, which function to express, store and transmit genetic information. The major radiation damages to the living things are essentially relative to the physical and chemical reactions of nucleic acids. Therefore, interests in photochemical reaction dynamics of nucleic acids have been intensified in recent years with the development of powerful experimental and computational techniques, boosting a challenging and promising subfield of chemical reaction dynamics interdisciplinary with molecular biology. In this context, we have made great efforts in developing the transient spectroscopic methods, particularly time-resolved infrared, to investigate the excited state and free radical reaction dynamics involved in the photochemical reactions of nucleic acid bases and DNA secondary structures (duplex, quadruplex etc.). By capturing the fast chemical events of these key short-lived transient species and combining quantum chemical calculations, we revealed the reaction mechanisms of [2+2] photocycloaddition, spore photoproduct (SP) photolesion, electron transfer, proton transfer, photosensitization, ROS oxidation, and photocleavage that are closely associated with the crosslink or oxidative DNA damages. The key roles of non-adiabatic surface intersections, excited state electronic structure property, conformation of secondary structure, base-pairing, π-stacking, and hydrogen-bonding in affecting the photochemical reaction pathways are elucidated. Our results provided important chemical insights to understand the DNA damage at the molecular and quantum state specific levels. This review mainly summarizes the recent progress made by our groups and the related work in literatures.