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Updated: Mar 8, 2026

Spectrophotometric Screening for Potential Inhibitors of Cytosolic Glutathione S-Transferases
Published on: October 10, 2020
Insights into ligand binding to a glutathione S-transferase from mango: Structure, thermodynamics and kinetics
Ignacio Valenzuela-Chavira1, Carmen A Contreras-Vergara2, Aldo A Arvizu-Flores3
1Laboratorio de Estructura Biomolecular, Centro de Investigación en Alimentación y Desarrollo, A.C. (CIAD), Hermosillo, Sonora 83304, Mexico; Laboratorio de Genética Molecular de Plantas, Centro de Investigación en Alimentación y Desarrollo, A.C. (CIAD), Hermosillo, Sonora 83304, Mexico.
Abstract:
We studied a mango glutathione S-transferase (GST) (Mangifera indica) bound to glutathione (GSH) and S-hexyl glutathione (GSX). This GST Tau class (MiGSTU) had a molecular mass of 25.5 kDa. MiGSTU Michaelis-Menten kinetic constants were determined for their substrates obtaining a Km, Vmax and kcat for CDNB of 0.792 mM, 80.58 mM min-1 and 68.49 s-1 respectively and 0.693 mM, 105.32 mM min-1 and 89.57 s-1, for reduced GSH respectively. MiGSTU had a micromolar affinity towards GSH (5.2 μM) or GSX (7.8 μM). The crystal structure of the MiGSTU in apo or bound to GSH or GSX generated a model that explains the thermodynamic signatures of binding and showed the importance of enthalpic-entropic compensation in ligand binding to Tau-class GST enzymes.
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