Typically, there are specific molecular interactions between a substrate and enzyme, which occur during enzymatic catalysis, that must be sufficient to not only reduce the transition state barrier appropriate for the reaction but also define a particular (usually small) set of chemical reactions. Both the origins and strengths of these interactions are fundamental issues in understanding how enzymes work. While more structural information is increasingly available from X-ray crystallographic studies, the extent of these interactions and the electronic character of the substrate and nearby protein groups within the active site generally must be simply surmised from the structural data and kinetic studies. Rarely are these molecular properties directly measured. We have approached this problem by determining the vibrational spectra of bound substrates using Raman spectroscopy. The observed vibrational frequencies are a measure of force constants between particular atoms, and these constants can be related in turn to bond orders and electronic distributions between these atoms.