The primary goal of this research is to gain insight into the role that the L and M polypeptides of the bacterial photosynthetic reaction center play in determining the parameters of electron transfer between reaction center chromophores. To this end, sophisticated spectroscopic techniques will be combined with molecular genetic manipulation of the amino acid sequences of these polypeptides for the analysis of reaction center function. Specific methods to be employed include picosecond resolution fluorescence decay measurements, subpicosecond resolution transient absorption spectroscopy of electron transfer intermediates, cassette mutagenesis of reaction center genes, and the production of chimeric reaction centers by forcing deletions in the reaction center genes of one organism to be repaired by reaction center sequences derived from a related organism. This work will result in a better understanding of the specific electron transfer reactions involved in the primary events of photosynthesis and provide new insights into the dielectric nature of proteins in general.
