1. Department of Biochemistry, Center for Chemistry and Chemical Engineering, Lund University, PO Box 124, S-221 00, Lund, Sweden; Department of Chemistry, University of York, Heslington, YO10 5DD, York, UK.; and CERMAV−CNRS, BP 53, 38041, Grenoble Cedex 9, France, affiliated with the Joseph Fourier University of Grenoble, France