Dynamics of Excited Electronic States in DNA Strands

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With this awwrd, the Chemical Structure Dynamics and Mechanisms-A (CSDM-A) Program of the Division of Chemistry is funding Professor Bern Kohler of Montana State University to investigate the photophysics of double-stranded DNA. Double-stranded DNA appears to have enhanced stability against photo-degradation, and the Kohler group is undertaking a detailed investigation to better understand the mechanistic underpinnings of this photochemical stability. In additional experiments, Prof. Kohler and his research students will investigate how the photochemistry of DNA differs in so-called deep eutectic solvents (DES). Prof. Kohler's research has important implications in biology and medicine, in that understanding the way DNA interacts with light has direct bearing on understanding the ways that ultraviolet light from the sun can damage skin. Students working in the Kohler laboratory receive training at the interface of physical chemistry and biology, as preparation for careers in the acedemic or biotechnology sectors.The Kohler research group includes active participation of undergraduate students in authentic research. In addition, Prof. Kohler and his group members are engaged in outreach to K-12 students and teachers in the state of Montana, through a variety of established programs, such as Montana State University's Science Math Resource Center and the Montana Space Grant Consortium.Professor Bern Kohler and his research group will conduct detailed photochemistry experiments using ultrafast laser methods to investigate the interesting photophysics of double-stranded DNA. Questions remain as to how exactly double-stranded DNA photochemically decays after electronic excitation. In the present award, Professor Kohler and his group will conduct a number of experiments to develop a better understanding of the photochemical details. Experiments to be conducted include: (1) a study of concerted proton-electron transfer (CPET) in AT and GC DNA using time-resolved infrared (TRIR) spectroscopy; (2) a collaborative study with Dr. Kimberly de La Harpe of the USAF Academy on the photochemistry of an oligonucleotide with TRIR spectroscopy that has been studied previously with UV/Visible transient absorbance (TA) spectroscopy; (3) a TRIR and TA study of miniduplexes synthesized for the Kohler group in a collaboration with Prof. Cynthia Burrows of the University of Utah; and (4) a new thrust investigating the photochemistry of DNA in DES's. Experimental work will benefit from insight provided by the theoretical group of Professor Roberto Improta of the National Research Council of Italy's Institute of Biostructures and Bioimaging.