Oxidation of GMP in the presence of lysine: A simple model system for DNA-protein cross-linking

CHED 912

Justine Danielle Ott, justott@msmc.la.edu, Kimberly Rebello, kimbrebe@msmc.la.edu, Christina B. Evangelista, chrievan@msmc.la.edu, Eunice Lee, eunilee@msmc.la.edu, and Eric D. A. Stemp. Department of Physical Sciences and Mathematics, Mount St. Mary's College, 12001 Chalon Road, Los Angeles, CA 90049
Oxidative damage is a significant contributor to cancer and various neurodegenerative diseases, such as Parkinson's and Alzheimer's, and guanine is particularly vulnerable to oxidation. One possible consequence of oxidative damage is formation of DNA-protein crosslinks. Here, a simple model system was used to detect guanine-lysine crosslinks, a likely consequence of oxidative DNA-protein crosslinking. In this system, a photochemical method, the Flash-Quench technique, was used to oxidize guanosine-5'-monophosphate (GMP), and the resulting radical was reacted with lysine, creating guanine-lysine crosslinks. The material was analyzed by HPLC. The unreacted mixture gives a chromatogram with separate peaks absorbing at 230 and 260 nm. The irradiated mixture gives similar peaks, with additional smaller peaks absorbing at both 230 and 260-290 nm, suggesting formation of a guanine adduct. Once the guanine-lysine crosslinks are produced in higher yields from the simple model systems, they will be analyzed using Nuclear Magnetic Resonance (NMR) Spectroscopy and Mass Spectrometry.