DNA absorbs ultraviolet light and the absorption of UV light is the primary cause of photochemical damage to DNA, resulting in significant problems such as cell death and skin cancer. Luckily, nucleic acids are incredibly efficient at dissipating the electronic excitation quickly and thereby avoiding photochemical damage. Our research studies the fundamental photophysics of DNA in order to understand the mechanisms by which it usually avoids photodamage and the molecular situations that lead to photodamage.
Our lab applies methods in physical chemistry to the study of the ultrafast photophysics of DNA following its absorption of ultraviolet light. In one project, we are determining the mechanisms by which single nucleic acids are able to efficiently relax to the ground electronic state. It has previously been established that the individual nucleic acids undergo non-radiative decay back to the ground state within 1 ps of absorbing UV light. Our work aims to determine the structural changes in the nucleic acids that drive this ultrafast process. In a related project, we are determining the quantum yield of photodamage in short DNA oligomers, such as TT, AATT, or ATTA. In these systems, photochemical dimerization of the two adjacent thymines is the primary lesion caused by exposure of DNA to ultraviolet light, which can eventually lead to cell death and cancer. We have used chemical actinometry, NMR, molecular dynamics, and femtosecond transient absorption to understand the mechanism of dimerization and the protective effects of adjacent adenines.
People on this project:
- Joohyun Lee
Publications for this project
Ultraviolet light makes dGMP floppy: Femtosecond stimulated Raman spectroscopy of 2_-deoxyguanosine 5_-monophosphate. Submitted to J. Phys. Chem. B, 2017