Exploration of the P3 region of PEXEL peptidomimetics leads to a potent inhibitor of the Plasmodium protease, plasmepsin V

Publication date: Available online 16 March 2016
Source:Bioorganic & Medicinal Chemistry
Author(s): Michelle Gazdik, Kate E. Jarman, Matthew T. O'Neill, Anthony N. Hodder, Kym N. Lowes, Helene Jousset Sabroux, Alan F. Cowman, Justin A. Boddey, Brad E. Sleebs
The use of arginine isosteres is a known strategy to overcome poor membrane permeability commonly associated with peptides or peptidomimetics that possess this highly polar amino acid. Here, we apply this strategy to peptidomimetics that are potent inhibitors of the malarial protease, plasmepsin V, with the aim of enhancing their activity against Plasmodium parasites, and exploring the structure-activity relationship of the P³ arginine within the S3 pocket of plasmepsin V. Of the arginine isosteres trialled in the P³ position, we discovered that canavanine was the ideal and that this peptidomimetic potently inhibits plasmepsin V, efficiently blocks protein export and inhibits parasite growth. Structure studies of the peptidomimetics bound to plasmepsin V provided insight into the structural basis for the enzyme activity observed in vitro and provides further evidence why plasmepsin V is highly sensitive to substrate modification.

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