While at UCSD, he examined the ability of a pigment-protein complex known as the bacterial reaction center to perform the primary processes in photosynthesis, the conversion of light energy into a charge-separated state. As part of these studies, he was part of a group that pioneered structural studies of membrane proteins as they determined three-dimensional structure of the bacterial reaction center. This experience has evolved to his current research interests in biophysics and biochemistry with a focus on the role of proteins in energy and disease.