Dependence of oxidative DNA protein-cross-linking on GC content

CHED 901

Carmen E. Ochoa, carmocho@msmc.la.edu1, Tiffany Maisonet, tiffmais@msmc.la.edu1, Jessica Zelaya1, Maricela Alvarez-Montez1, and Eric D. A. Stemp2. (1) Department of Physical Sciences and Mathematics, Mount St. Mary's College, 12001 Chalon Road, Los Angeles, CA 90049, (2) Department of Physical Sciences and Mathematics, Mount St. Mary's College, 12001 Chalon Road, Los Angeles, CA 90049
To determine the effect of GC content on oxidative DNA-protein crosslinking, guanine oxidation was induced in several DNAs by the flash quench technique and the crosslinking was quantified by the chloroform extraction assay. With poly(dA-dT), poly(dG-dC) and calf thymus DNA, the crosslinking with histone decreased in the order: calf thymus> poly(dG-dC)> poly(dA-dT). As expected, there was no crosslinking for poly(dA-dT), which lacks guanine. Surprisingly, calf thymus DNA exhibited the highest reaction yield, even though it is only 42% GC. To understand this result better, we examined the crosslinking of natural DNAs from Microccocus lysodeikticus (72% GC), calf thymus (42% GC) and Clostridium perfringens (29% GC) with both histone and cytochrome c. The crosslinking decreased in the order: M.L > C.T> C.P for cytochrome c. For histone, the trend was C.T ~ C.P> M.L., which suggests that the binding affinity for histone strongly influences the crosslinking yield for a given DNA.
 

Undergraduate Research Poster Session: Biochemistry
2:00 PM-4:00 PM, Monday, March 26, 2007 Hyatt Regency Chicago -- Riverside Center, Poster

Division of Chemical Education

The 233rd ACS National Meeting, Chicago, IL, March 25-29, 2007