Figure 1 shows the influence of solvent on the first electronic excited state. Large solvent effects result in a large destabilization of the diffuse atomic-like Rydberg states, and in a small solvent cavity, such states are not observed. We are assessing the applicability of these charge distributions in calculations of the circular dichroism of proteins. It provides a coarse measure of the secondary structure of a protein in solution. We are developing the theoretical basis of circular dichroism to further our understanding of how protein conformation determines the circular dichroism spectra.
Circular dichroism arises from the electronic transitions of chiral compounds.
We are using quantum chemistry calculations to investigate the electronic absorption spectra of small amides. In parallel with the ab initio approach, we are also investigating an empirical derivation of parameters to describe the electronic states of the amide chromophore. These parameters will be used to develop a quantitative method to calculate the circular dichroism of given protein structures and thus provide the connection between the atomic-detailed structure of proteins and their circular dichroism spectra. The advent of combinatorial chemistry technologies demands the development of fast and accurate quantitative structure-activity relationships, with the goal of directing the robotic synthesis of compounds in real time. We have developed a fast and reliable method for deriving nonlinear quantitative structure-activity relationships.