Proton pump inhibitors drastically modify triosephosphate isomerase from Giardia lamblia at functional and structural levels, providing molecular leads in the design of new antigiardiasic drugs

• Published in: Biochimica et biophysica acta Vol. 1860; no. 1; pp. 97 - 107
• Main Authors: García-Torres, Itzhel, de la Mora-de la Mora, Ignacio, Marcial-Quino, Jaime, Gómez-Manzo, Saúl, Vanoye-Carlo, América, Navarrete-Vázquez, Gabriel, Colín-Lozano, Blanca, Gutiérrez-Castrellón, Pedro, Sierra-Palacios, Edgar, López-Velázquez, Gabriel, Enríquez-Flores, Sergio
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.01.2016
• Subjects: cytotoxicity; Drug Design; drugs; enzyme activity; Enzyme Stability; Giardia lamblia; Giardia lamblia - drug effects; Giardia lamblia - enzymology; glycolysis; Humans; Hydrophobic and Hydrophilic Interactions; hydrophobicity; Mass Spectrometry; mutants; Proton pump inhibitors; Proton Pump Inhibitors - pharmacology; Structural perturbation; Sulfenamide; thermal stability; triose-phosphate isomerase; Triose-Phosphate Isomerase - antagonists & inhibitors; Triose-Phosphate Isomerase - chemistry; Triose-Phosphate Isomerase - physiology; Triosephosphate isomerase; Sulfenamide; Proton pump inhibitors; Giardia lamblia; Triosephosphate isomerase; Structural perturbation
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/j.bbagen.2015.10.021

Proton pump inhibitors (PPIs) are extensively used in clinical practice because of their effectiveness and safety. Omeprazole is one of the best-selling drugs worldwide and, with other PPIs, has been proposed to be potential drugs for the treatment of several diseases. We demonstrated that omeprazole shows cytotoxic effects in Giardia and concomitantly inactivates giardial triosephosphate isomerase (GlTIM). Therefore, we evaluated the efficiency of commercially available PPIs to inactivate this enzyme. We assayed the effect of PPIs on the GlTIM WT, single Cys mutants, and the human counterpart, following enzyme activity, thermal stability, exposure of hydrophobic regions, and susceptibility to limited proteolysis. PPIs efficiently inactivated GlTIM; however, rabeprazole was the best inactivating drug and was nearly ten times more effective. The mechanism of inactivation by PPIs was through the modification of the Cys 222 residue. Moreover, there are important changes at the structural level, the thermal stability of inactivated-GlTIM was drastically diminished and the structural rigidity was lost, as observed by the exposure of hydrophobic regions and their susceptibility to limited proteolysis. Our results demonstrate that rabeprazole is the most potent PPI for GlTIM inactivation and that all PPIs tested have substantial abilities to alter GITIM at the structural level, causing serious damage. General significance. This is the first report demonstrating the effectiveness of commercial PPIs on a glycolytic parasitic enzyme, with structural features well known. This study is a step forward in the use and understanding the implicated mechanisms of new antigiardiasic drugs safe in humans. •Proton pump inhibitors (PPIs) are extensively used in clinical practice because of their effectiveness and safety in humans.•The glycolytic enzyme triosephosphate isomerase from Giardia lamblia (GlTIM) is a good target to generate antigiardiasic drugs.•All the proton pump inhibitors efficiently inactivate and desestabilizate the GlTIM at functional and structural levels.•Rabeprazole represents a promising lead in the search of new antigiardiasic drugs.•The mechanisms of action of the PPIs on GlTIM can be helpful to understand their effectiveness and safety in human.