1. Chemistry Research LaboratoryDepartment of ChemistryUniversity of Oxford 12 Mansfield Road Oxford OX1 3TA UK
2. Current address: GSKMedicines Research Centre Gunnels Wood Road Stevenage SG1 2NY UK
3. Current address: Department of Molecular MedicineFaculty of MedicineUniversity of Malaya, Jalan Universiti 50603 Kuala Lumpur Malaysia
4. Department of BiochemistryUniversity of Oxford South Parks Road Oxford OX1 3QU UK