STRUCTURE AND FUNCTION OF THE PHOTOSYNTHETIC REACTION-CENTER FROM RHODOBACTER-SPHAEROIDES

The three-dimensional structure of the photosynthetic reaction center from Rhodobacter sphaeroides is described. The reaction center is a tr ansmembrane protein that converts light into chemical energy. The prot ein has three subunits: L, M, and H. The mostly helical L and M subuni ts provide the scaffolding and the finely tuned environment in which t he chromophores carry out electron transfer. The details of the protei n-chromophore interactions are from studies of a trigonal crystal form that diffracted to 2.65-angstrom resolution. Functional studies of th e multi-subunit complex by site-specific replacement of key amino acid residues are summarized in the context of the molecular structure.