9723469 Bryant The cyanobacterial Photosystem I reaction center is a light-driven oxidoreductase catalyzing the transfer of electrons from reduced cytochrome c553 (or plastocyanin) to oxidized ferredoxin (or flavodoxin). The long-term goal of this research program is to understand the biogenesis of this complex enzyme, as well as the structural and mechanistic details that allow it to catalyze the above mentioned reaction with a quantum yield approaching 1.0 and a very high thermodynamic efficiency (~45%). Taking advantage of knowledge gained during the prior funding period, powerful methods of site-directed mutagenesis, protein overproduction, biochemical resolution and reconstitution, chemical rescue and modification, and kinetic optical and EPR spectroscopies will be used to produce and analyze PS I reaction centers with novel properties. Photosynthesis in plants, algae and cyanobacteria is the major source of biological energy and oxygen on the earth. The investigator's work will increase the knowledge of photosynthesis and will provide information that can potentially be used for genetic manipulation of photosynthesis in crop plants
