Optical Activity of Amino Acids: A Comparison of Theory and Experiment

Molecules that contain at least one chiral center exhibit a physical property known as optical activity. Theoretically, it can be studied through the use of an initio quantum mechanical calculation. The optical activity can also be measured experimentally using a polarimeter. It does this by measuring the rotation of plane polarized light produced by a solution containing chiral molecules. A biologically relevant molecule that contains a chiral center would include several different amino acids. The optical activity of amino acids is dependent on pH due to the effects of charge on the conformation of the structure. In this study, we compared the optical rotation measurements for several amino acids with varying pH to the results predicted by several computational methods. The degree to which the theoretical models agree with experimental data is discussed in terms of the limitations of the models.