1Biophysics Department, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF, UK
2Molecular Structure Corporation, 3200 Research Forest Drive, The Woodlands, TX 77381, USA
3UPR 180 CNRS, Lab. de Physique, Faculle de Phannacie,
92290 Chatenay Malabry, France
4Parke-Davis Phannaceuticals, ABL Basic Research Program, PO Box B, Bldg. 539, Frederick MD 21702, USA