Time-resolved crystallography for protein structure: the case of heme proteins

Time-resolved Laue diffraction is an elegant approach by which polychromatic X-ray pulses are used in combination with rapid laser triggering of light-sensitive samples so as to make a movie of protein reaction dynamics in real time. The current state-of-the-art with protein Laue diffraction has been time-resolved studies of light-induced conformational changes in myoglobin-CO with 150 ps resolution. Myoglobin has traversed the whole history of pump–probe Laue diffraction, yielding a massive amount of data that have provided considerable insight into the understanding of protein dynamics. A picture of factors governing myoglobin dynamics following ligand dissociation has been drawn from data arising from wild-type and mutant proteins. Other heme proteins have been studied using this approach: Scapharca inequivalvis dimeric hemoglobin, the FixL PAS domain and the photosynthetic reaction center complex of Blastochloris viridis.