Professor Sage’s research is motivated by a fascination with the physical basis for the function of proteins. He develops and applies novel spectroscopic approaches to understand the structure, dynamics, and function of biological macromolecules. Infrared protein crystallography uses polarized infrared measurements on oriented protein crystals to identify reaction intermediates and refine the structure of protein active sites. A new synchrotron-based technique, nuclear resonance vibrational and reactive dynamics of iron in these complex molecules.