This project introduces the spectroscopic techniques of circular dichroism and stopped-flow absorption methods to the chemistry laboratory curriculum. Spectroscopy is among the most fundamental of physical measurements, with extensive applications to all areas of chemistry. However, the previously available spectroscopic tools within the Chemistry Department have limited the ability to address such structural questions as the distribution of conformations within a macromolecular sample or the change in substrate conformation upon ligand binding. Furthermore, the lack of fastmixing techniques has reduced the accuracy of kinetic studies of fast reactions in solution (typically those reactions with half-lives on the order of 10 ms to 10 s). The new instrumentation facilitates the examination of the absorption of circularly polarized light by chiral systems and the elucidation of time-dependent phenomena in aqueous solution using stopped flow methods. Initial experiments allow students to observe the sensitivity of circular dichroism to a variety of conformational and organizational changes and to experience the utility of stopped-flow methods for examining fast reactions in solution. The principles underlying these techniques have already been presented in three lecture courses in the department: physical chemistry, biochemistry, and biophysical chemistry. The new instrumentation enhances the kinetic offerings in the existing sophomore physical chemistry laboratory and helps initiate a biochemistry laboratory for the newly approved biological chemistry option for chemistry majors. The instrumentation also expands the range of questions that senior majors can address in the required Introduction to Research course, including the characterization of the cation effect in biochemical systems and of the influence of phase behavior on the optical activity of metal-containing liquid crystals.
