Recent progress has opened X-ray crystallography to the study of integral membrane pigment-protein complexes. Currently, detailed structural information is only available for a limited class of these complexes, reaction centers from purple bacteria. To extend our knowledge, we are studying other types of complexes, such as the light-harvesting complex, and complexes from other organisms, such as reaction centers from green bacteria. We hope that such studies will provide insight into the photosynthetic process that occurs in the evolutionary diverse range of biological systems.
An example of an ongoing project is the characterization of the reaction center from the purple bacterium Rhodobacter sphaeroides. By X-ray diffraction studies we determined the structure of the pigments and protein. The striking division of the pigments into two symmetrical branches is surprising because only one branch is active. The transfer of electrons along the active branch is being investigated by a variety of techniques. The pigment composition can be changed by biochemical manipulation and the pigment environment can by changed by site-directed mutagenesis. The structural and functional characteristics of the altered complexes are then studied by X-ray diffraction, optical spectroscopy, and magnetic resonance.
Tel: 1-(480) 965-8241
Fax: 1-(480) 965-2747
Email: AllenJ@asuchm.la.asu.edu
Office Room Number: Physical Sciences PS C-235
Lab Room Number: Physical Sciences PS C-134/PS C-44
