Scientists using extremely high powered X-rays and a pulsed laser have succeeded in taking the first "snapshots" of a photoactive protein molecule as it converts light energy into chemical energy, a process that takes less than one billionth of a second.
The finding, reported in today's issue of the journal Science, provides the first direct structural evidence of how light can be converted into chemical energy -- the initial stage of processes as different, and as fundamental, as photosynthesis and vision. It also may suggest a powerful new mechanism for the development of optical computers.
The ability to record this ultra-rapid conversion results from a recent, million-fold improvement in time resolution of X-ray measurements that can now record changes in the shape of the working protein that occur in billionths of a second.
The experiments, only the second of their type, were performed by an international team at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. About one year ago, a related team reported the first nanosecond movie of the muscle protein myoglobin as it opened up to release carbon monoxide. Today's report emphasizes the wider applicability of this new type of measurement.
Keith Moffat, Ph.D., professor of biochemistry and molecular biology and director of the Consortium for Advanced Radiation Sources at the University of Chicago, who led both research teams, and colleagues from the University of Chicago, ESRF, Lund University and the E.C. Slater Institute of the University of Amsterdam, Netherlands, focused on a blue light photo-reactive protein called xanthopsin, found in the eubacterium Ectothiorhodospira halophila. These bacteria respond to the absorbtion of light by altering their swimming behavior.
This bacterium, so far found only in a few high arid lake beds in Oregon and
salt depressions in the Egyptian desert, is "rather obscure," says Moffat, but
this simple organism appears to be quickly
Contact: John Easton
University of Chicago Medical Center