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© Centre for Modeling & Simulation, Savitribai Phule Pune University
| Savitribai Phule Pune University |
| Title | Photoinduced electron transfer in DNA repair: A computational study |
| Speaker |
Abdul Rehaman Moughal Shahi,
International Institute of Information Technology, Hyderabad
Dr. Abdul Rehaman Moughal Shahi is an INSPIRE faculty at the International Institute of Information Technology, Hyderabad. He is a computational chemist, with research focus in the area of photochemistry and photobiology. He is intereted in modeling complex light induced biochemical processes using computational chemical methodologies. |
| Date & Time | Monday, 20 July 2015 | 15:00-16:00 |
| Venue |
Kelkar Lab Centre for Modeling and Simulation, Savitribai Phule Pune University |
| Abstract | UV radiation (200-400 nm) causes damage of DNA, mostly producing the cyclobutane pyrimidine and (6-4)-pyrimidine-pyrimidone (PP) photodimers. (6-4) photolyase is a DNA repair enzyme that selectively repairs (6-4)PP photodimer, using visible light. This repair process is a complex photocycle comprising of several electron transfer (ET) steps possibly coupled to proton transfer, controlled by the protein. The key repair steps are the forward electron transfer (FET) and the back electron transfer (BET) which involve the FADH− chromophore and the (6-4)PP. Experimentally, the ET rates of these steps have been estimated, but the overall repair mechanism remains elusive. We wish to predict the ET rates with in the photolyase repair site and evaluate the roles of various factors that may influence these ET rates. Towards this, we have set up a multiscale computational apparatus based on a combination of QM, hybrid QM/MM and MD methodologies. With this approach, we have computed the energies of the FADH− - (6-4) PP (Donor-Acceptor) complex in different electronic states, formally describing the electron transfer reaction. We then evaluate the effects of the protonation state of key residues, the solvent and DNA counterions on these states and also account for the effect of the protein dynamics. Using these complex energy estimates, we predict the FET and BET rates employing the semi classical Marcus formalism and compare them against the experimental observations. |
| Organizer/Host | Centre for Modeling and Simulation, Savitribai Phule Pune University |
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