Abstract
Aspects of intramolecular light energy and electron transfer will be discussed for three protein cofactor complexes, whose three‐dimensional structures have been elucidated by X‐ray crystallography: components of light‐harvesting cyanobacterial phycobilisomes, the purple bacterial reaction centre and the blue multi‐copper oxidases. A wealth of functional data is available for these systems which allow specific correlations between structure and function, and general conclusions about light energy and electron transfer in biological materials to be made.