Structure of photosynthetic complexes

Photosynthesis, the source of energy for most of life on Earth, spans a wide range of time and length scales in its fundamental processes.  The initial events of light absorption and energy transfer between neighbouring (~1 nm separation) pigments (bacteriochlorophylls (BChls), chlorophylls (Chls), carotenoids (crts)) within a light-harvesting complex (LHC) occur on a femtosecond timescale. Excitation energy migrates between LHCs in membranes over distances of 10-200 nm and tens of picoseconds later it arrives at a specialised complex, the reaction centre, initiating a picosecond charge separation. Milliseconds later the doubly reduced quinol acceptor leaves the RC and diffuses a few nm in the membrane to the cytochrome bc1/ b6f complex. Subsequent generation of a proton-motive force across the photosynthetic membrane, and the eventual storage of this energy in a chemical form as ATP (ATP synthase) take tens of ms.

Stored solar energy in the form of a protonmotive force and ATP fuel cellular metabolism, and ultimately the proliferation of new membranes and cells on a timescale of hours. 

Using Cryo-EM we study the structure and function of these photosynthetic machines.