Inhibitor binding to the plasmepsin IV aspartic protease from Plasmodium falciparum

Area of Science:

• Biochemistry
• Medicinal Chemistry
• Parasitology

Background:

• Plasmepsin IV (Plm IV) is an aspartic protease in the malaria parasite *Plasmodium falciparum*.
• Plm IV plays a key role in degrading host hemoglobin within the parasite's food vacuole.
• Inhibiting Plm IV is a potential strategy for antimalarial drug development.

Purpose of the Study:

• To experimentally and theoretically evaluate the inhibitory activity of previously synthesized plasmepsin inhibitors against Plm IV.
• To identify structural determinants of inhibitor binding to Plm IV.
• To explore the potential for developing selective Plm IV inhibitors.

Main Methods:

• Synthesis and experimental testing of plasmepsin inhibitors with a 1,2-dihydroxyethylene transition state mimic.
• Application of Linear Interaction Energy (LIE) method and empirical scoring functions for theoretical binding affinity prediction.
• Molecular dynamics (MD) simulations to analyze inhibitor-enzyme interactions and binding pocket features.

Main Results:

• A symmetric oxadiazole-based inhibitor, lacking amide bonds, was identified as the most potent inhibitor of Plm IV both experimentally and theoretically.
• Experimental binding affinities correlated well with theoretical predictions using LIE and scoring functions.
• MD simulations provided insights into the structural basis for potent inhibition and revealed key features of the Plm IV binding pocket.

Conclusions:

• The study successfully identified a highly effective inhibitor for Plm IV, offering a promising lead for antimalarial drug discovery.
• Computational methods, including LIE and MD simulations, are valuable tools for understanding inhibitor-enzyme interactions and guiding drug design.
• Understanding the Plm IV binding pocket in comparison to related enzymes can aid in the rational optimization of future inhibitors.