Photolysis of the carbon monoxide complex of myoglobin: nanosecond time-resolved crystallography.

The biological activity of macromolecules is accompanied by rapid structural changes. The photosensitivity of the carbon monoxide complex of myoglobin was used at the European Synchrotron Radiation Facility to obtain pulsed, Laue x-ray diffraction data with nanosecond time resolution during the process of heme and protein relaxation after carbon monoxide photodissociation and during rebinding. These time-resolved experiments reveal the structures of myoglobin photoproducts, provide a structural foundation to spectroscopic results and molecular dynamics calculations, and demonstrate that time-resolved macromolecular crystallography can elucidate the structural bases of biochemical mechanisms on the nanosecond time scale.