[Congress Report]

Time-resolved crystallography and protein dynamics

The session ranged from X-ray crystallographic studies using 3D crystals and electron microscopic studies using 2D crystals to simulations and molecular dynamics calculations. G. Petsko (Brandeis U.) presented an overview of time-resolved crystallography, the methods for and problems with triggering reactions in crystals, the Laue method on fast time scales and slowing and trapping approches. H. Kato (Kyoto U.) described a phosphorylation reaction of glutathion synthetase using photolysis of caged ATP to start the reaction. Time-resolved Laue and cryocrystallographic experiments were performed that showed the build-up of the phosphorylated transition state analog and the concomitant ordering of a loop. R. Henderson (MRC) used electron microscopy, photolysis and freeze trapping to look at the structures of reaction intermediates in 2D crystals of wildtype and a mutant bacteriorhodopsin. J. Hajdu (Uppsala U.) reported results obtained by an EU collaboration on the use of free electron lasers for structure determination. Simulations indicated that 10 fs pulse length might result in diffraction before the sample disappears in a plasma, whereas this seemed not to be true for 70 fs pulses. Protein dynamics were addressed by G. Bradbrook (Grenoble). The importance of water molecules and protons was taken up again in the summary of the session by J. Helliwell (Manchester U.) who also addressed the complementarity of neutron diffraction experiments with atomic resolution X-ray studies.

Ilme Schlichting