1. Department
of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, BMC
Box 596, S-751 24 Uppsala, Sweden
2. Chemistry
Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K.
3. Physical
and Theoretical Chemistry Laboratory, University of Oxford, South Parks
Road, Oxford OX1 3QZ, U.K.