Journal of Medicinal Chemistry Author Contributions §These authors contributed equally to the work. ’ ACKNOWLEDGMENT We thank Gina McKay for performing high resolution mass spectrometry analyses and for assistance with performing other NMR and MS analyses, Daniel James, for data management, Dr. Sandra Oza for cloning the His-tagged T. brucei TryR, Irene Hallyburton and Bhavya Rao for enzyme and cell screening assays, Daniel Spinks and Dr. Laura Cleghorn for synthetic investigations and compound selection during the early stages of this research programme, and staﬀ at the European Synchro- tron Radiation Facility for support with synchrotron data collec- tion. A.H.F. is a Wellcome Principle Research Fellow, funded by grants from the Wellcome Trust (WT 07938, WT 077705 and WT 083481). 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