Observing myoglobin proteinquake with an X-ray free-electron laser

The events following the photodissociation of the bond be- tween myoglobin and its ligand have been extensively studied with a variety of experimental, theoretical and computational methods [1]. The results of these investigations have been rationalized in terms of a model that implies a protein quake- like motion [2], i.e. the propagation of the strain released upon photoexcitation through the protein similar to the prop- agation of acoustic waves during an earthquake. The exper- imental investigations performed so far have been based on spectroscopic measurements or did not have sufficient time- resolution to measure the timescale of such “proteinquake”. We have obtained direct experiment…