Monday, 23 May 2005

This presentation is part of: Spectroscopy of Biomolecules Posters

A Stark Spectroscopic Study of Semiquinone FAD in DNA Photolyase

Goutham Kodali, M. Salim Siddiqui, and Robert J. Stanley. Temple University, Philadelphia, PA

DNA photolyase is a light-driven flavoprotein that repairs cyclobutylpyrimidine dimers (CPD) in UV-damaged DNA via an ultrafast photoinduced electron transfer reaction from the fully-reduced anionic flavin adenine dinucleotide (FADH-) cofactor to the CPD. Previously we have demonstrated the possibility that the electric dipole moment of the CPD induces an electrochromic shift in the absorption spectrum of the oxidized FAD cofactor in DNA photolyase. These results would indicate that the substrate electric field plays a critical role in the electron transfer process. A similar electrochromic shift has been reported by the Schelvis group (NYU) for semiquinone DNA photolyase upon CPD binding. In an effort to provide further insight into this result, we have explored the electronic structure of the ground and excited electronic states of the semiquinone FAD in DNA photolyase using Stark spectroscopy.

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