1. Institute of Physiology and Pathophysiology; Friedrich-Alexander-Universität Erlangen-Nürnberg; Bavaria Germany
2. Biological Chemistry and Crop Protection Department; Rothamsted Research, Harpenden; Hertfordshire AL5 2JQ UK
3. Department of Parasitology, Global Drug Discovery; Bayer Animal Heallth GmbH; 51368 Leverkusen Germany
4. Department of Crystallography, Birkbeck College; University of London; London WC1E 7HX UK