The top pose (in terms of both docking score and Emodel) of 1d, the only selected compound with an amine-based 3-atom-length linker, was predicted to fit reasonably well in TbPTR1, with the tail in subpocket C and one halogen bond formed between the meta-Cl and the backbone carbonyl oxygen of Trp221 (Fig. ). The N-cyclopropyl substituent is in the vicinity of Cys168, Trp221 and Met213, with all of which it can potentially form closer contacts if some flexibility of the amine-based linker is assumed.