X-ray diffraction studies have made outstanding contributions to structural molecular biology. The advent of high-intensity synchrotron radiation sources, coupled with the revival of the Laue method, has now made possible the rapid collection of X-ray crystallography data. As a result, proteinand virus crystallography is now progressing from studies of equilibrium structures to time-resolved studies of structures at reaction stages. The full exploitation of the synchrotron Laue method for the study of dynamic events in crystals requires many developments in physics, chemistry, andbiochemistry: the papers presented in this volume aim to report some of the striking results that have already been obtained and to discuss and identify necessary future developments.

D.W.J. Cruickshank: Time-resolved macromolecular crystallography: introductory remarks and a little history; Keith Moffat, Ying Chen, Kingman Ng, Duncan McRee & Elizabeth D. Getzoff: Time-resolved crystallography: principles, problems and practice; Gian Luigi Rossi, Andrea Mozzarelli, Alessio Peracchi & Claudio Rivetti: Time course of chemical and structural events in protein crystals measured by microspectrophotometry; Hans D. Bartunik, Lesley J. Bartunik & Hans Viehmann: Time-resolved X-ray diffraction studies of enzymes under cryoconditions; J.R. Helliwell: Synchrotron X-ray crystallography techniques: time-resolved aspects of data collection; J.E.T. Corrie, Y. Katayama, G.P. Reid, M. Anson & D.R. Trentham: The development and application of photosensitive caged compounds to aid time-resolved structure determination of macromolecules; E.M.H. Duke, A. Hadfield, S. Walters, S. Wakatsuki, R.K. Bryan & L.N. Johnson: Time-resolved diffraction studies on glycogen phosphorylase b; Inger Anderson, Ian J. Clifton, Steven L. Edwards, Vilmos Fulop, Andrea T. Hadfield, Janos Hadju, Par Nordlund, Paul Phizackerley, Michael Soltis, Soichi Wakatsuki: On the scope and limitations of the Laue method in kinetic crystallography: studies with macromolecules; Axel Scheidig, Emil F. Pai, I. Schlichting, John Corrie, Gordon P. Reid, Alfred Wittinghofer & Roger S. Goody: Time-resolved crystallography on H-ras p21; Dagmar Ringe, Barry L. Stoddard, John Bruhnke, Paula Koenigs & Ned Porter: Can Laue catch Maxwell?: observation of short-lived species by Laue X-ray crystallography; Paul T. Singer, Robert P. Carty, Lonny E. Berman, Ilme Schlichting, Ann Stock, Arne Smalas, Zhouping Cai, Walter F. Mangel, Keith W. Jones & Robert M. Sweet: Laue diffraction as a tool in dynamic studies: hydrolysis of a transiently stable intermediate in catalysis by trypsin; A. Liljas, M. Carlsson, K. Hakansson, M. Lindahl, L.A. Svensson & A. Wehnert: Laue and monochromatic crystallography on carbonic anhydrase; D.M. Blow, P. Brick, C.A. Collyer, J.D. Goldberg & O. Smart: Conventional X-ray diffraction approaches to the study of enzyme mechanism: serine proteinases, aminoacyl-tRNA synthetases and xylose isomerase; Gregory A. Petsko: Art is long and time is fleeting: the current problems and future prospects for time-resolved enzyme crystallography.