1. Dainton Building, Department of Chemistry, University of Sheffield, Brook Hill, Sheffield, South Yorkshire S3 7HF, U.K.
2. GEO Specialty Chemicals, Hythe, Southampton, Hampshire SO45 3ZG, U.K.
3. School of Biosciences, University of Sheffield, Sheffield, South Yorkshire S10 2TN, U.K.
4. The Florey Institute for Host−Pathogen Interactions, University of Sheffield, Sheffield, South Yorkshire S10 2TN, U.K.