Carotenoid-Bacteriochlorophyll Interactions

Abstract

Carotenoids perform two major functions in bacterial photosynthesis [1, 2]. They act as photoprotective agents, preventing the harmful photodynamic reaction, and as accessory light-harvesting pigments, extending the spectral range over which light drives photosynthesis. Most bacterial carotenoids are rather hydrophobic molecules, and they are typically found associated with photosynthetic membranes. However, they are not freely mobile within the lipid interior of these membranes, but are rather non-covalently bound to the photochemical reaction centres and the light-harvesting complexes[3]. It is important to emphasise that it is the specific, close, wellordered interactions between the carotenoids and the bacteriochlorophyll molecules within these pigment-protein complexes that allows the carotenoids, efficiently, to fulfil their photoprotective and light-harvesting roles.