The conversion of light energy into chemical energy is one of the most
important processes in nature. By using light energy to oxidise
organic or inorganic compounds, photosynthetic organisms obtain the
electrons that are necessary for the fixation of carbon dioxide into
carbohydrate which is needed for cell growth. The initial
photochemistry occurs within membrane-bound pigment/protein complexes
known as reaction centre complexes (RCs). The elucidation of the
structure of the photosynthetic reaction centre complex from the
purple non-sulphur photosynthetic bacterium Rhodopseudomonas viridis
has formed a framework with which to understand the conversion of
light energy to chemical energy.