1. Theory of Condensed Matter Group, Department of Physics, University of Cambridge, Cambridge CB3 0HE, U.K.
2. Centre for Computational Biology, University of Birmingham, Birmingham B15 2TT, U.K.
3. Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham B15 2SY, U.K.
4. Bioinformatique Structurale, Institut Pasteur, CNRS URA 3528, CB3I CNRS USR 3756, 75724 Paris, France