Photosensitized Oxidation of G-Quadruplex Conformations of Guanine Derivatives

Participants: Rebecca Nolan (Biochemistry major, class of ‘09), Elyse Paterson (Biochemistry major, class of ‘09), Jack McSweeney (Chemistry major, class of ‘11)

Faculty: Dr. Jeremy McCallum, Department of Chemistry and Biochemistry

Abstract: Our genetic information is protected by single-stranded, Guanine-rich DNA called telomeres. These telomeres shorten with each cell division until a critical length is reached, whereby cells enter senescence and die. Telomeres naturally fold into G-quadruplex structures in vivo and are believed to be a main target of oxidative stress. This oxidative degradation of telomeres caused by reactive oxygen species (ROS) is purported to play a major role in telomere shortening. Understanding the mechanisms by which telomeres are degraded will shed insight into cell and organismal senescence.

Our research project involves using DNA models to study the mechanisms by which oxidative damage impacts G-quadruplex structures. Our group has synthesized several hydrophobic guanine derivatives to study G-quadruplex reactivity. The self-assembling properties of these model derivatives to form G-quadruplexes were studied by NMR techniques. Photosensitized oxidation of G-quadruplexes and detailed product analyses was conducted to understand the mechanisms of DNA quadruplex oxidative degradation.

Presentation: This work was presented at the Gordon Research Conference on Photochemistry and the Southern California Conference on Undergraduate Research (SCCUR).

Funding: This project has been supported by Continuing Faculty Research Grants through the Seaver College of Science and Engineering.

Image caption (above): Becky Nolan prepares a sample for NMR analysis.