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Updated: Jun 5, 2026

Spectrophotometric Screening for Potential Inhibitors of Cytosolic Glutathione S-Transferases
Published on: October 10, 2020
The extended catalysis of glutathione transferase
Raffaele Fabrini1, Alessio Bocedi, Kutayba F Dawood
1Department of Chemical Sciences and Technologies, University of Rome, Tor Vergata, Rome, Italy.
Abstract:
Glutathione transferase reaches 0.5-0.8 mM concentration in the cell so it works in vivo under the unusual conditions of, [S]≪[E]. As glutathione transferase lowers the pK(a) of glutathione (GSH) bound to the active site, it increases the cytosolic concentration of deprotonated GSH about five times and speeds its conjugation with toxic compounds that are non-typical substrates of this enzyme. This acceleration becomes more efficient in case of GSH depletion and/or cell acidification. Interestingly, the enzymatic conjugation of GSH to these toxic compounds does not require the assumption of a substrate-enzyme complex; it can be explained by a simple bimolecular collision between enzyme and substrate. Even with typical substrates, the astonishing concentration of glutathione transferase present in hepatocytes, causes an unusual "inverted" kinetics whereby the classical trends of v versus E and v versus S are reversed.
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