1. V. Šrajer, T.-y. Teng, C. Pradervand, Z. Ren, W. Schildkamp, K. Moffat, Department of Biochemistry and Molecular Biology and the Consortium for Advanced Radiation Sources, The University of Chicago, Chicago, IL 60637, USA.
2. T. Ursby and M. Wulff, European Synchrotron Radiation Facility (ESRF), 38043 Grenoble Cedex, France.
3. S.-i. Adachi, Biophysical Chemistry Laboratory, Institute of Physical and Chemical Research, Saitama 351-01, Japan.
4. D. Bourgeois, UPR 9015/IBS, 38027 Grenoble, France, and ESRF, 38043 Grenoble Cedex, France.