1. Astbury
Centre for Structural Molecular Biology and School of Molecular and
Cellular Biology, University of Leeds, Leeds LS2 9JT, U.K.
2. The
Swedish NMR Centre, University of Gothenburg, Box 465, 40530 Göteborg, Sweden
3. Department
of Chemistry and Molecular Biology, University of Gothenburg, Box 465, 40530 Göteborg, Sweden