Daniela Goga, Delmar Larsen
Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, CA 95618
Many biological events require the presence of light to activate; however, this is not always the case for enzymes. Many enzymes do not need exposure to light for activation, even though chromophoric (or light dependent) cofactors have been located on many of these structures. One example is aspartate aminotransferase (AAT), which utilizes the pyridoxal 5’-phosphate (PLP) cofactor to initiate a transmination reaction of aspartic acid. While light is not required for its activity, blue light illumination has been found to increase catalysis. The proposed model for this involves the deprotonation of a triplet state population of PLP to confirm this at a molecular level. We are using Gaussian, a quantum chemistry program, to develop a basic understanding of how the electronic structure, including pKa, changes upon different electronic states, including S0 (dark state), S1 (excited singlet state), and T1 (the low lying excited triplet state.) Currently, the calculations are still in progress. From these calculations, researchers in the fields of biomedicine and pharmacology will have a better understanding of mechanisms that AAT and PLP undergo and will be better able to apply them to their research.