title: Inhibition of human γ-glutamyl transpeptidase: development of more potent, physiologically relevant, uncompetitive inhibitors.
abstract: GGT (γ-glutamyl transpeptidase) is an essential enzyme for maintaining cysteine homoeostasis, leukotriene synthesis, metabolism of glutathione conjugates and catabolism of extracellular glutathione. Overexpression of GGT has been implicated in many pathologies, and clinical inhibitors of GGT are under development for use in the treatment of asthma, cancer and other diseases. Inhibitors are generally characterized using synthetic GGT substrates. The present study of uncompetitive inhibitors of GGT, has revealed that the potency with which compounds inhibit GGT activity in the standard biochemical assay does not correlate with the potency with which they inhibit the physiological reaction catalysed by GGT. Kinetic studies provided insight into the mechanism of inhibition. Modifications to the sulfobenzene or distal benzene ring of the uncompetitive inhibitor OU749 affected activity. One of the most potent inhibitors was identified among a novel group of analogues with an amine group para on the benzosulfonamide ring. New more potent uncompetitive inhibitors of the physiological GGT reaction were found to be less toxic than the glutamine analogues that have been tested clinically. Development of non-toxic inhibitors is essential for exploiting GGT as a therapeutic target.
authors.affiliation: Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Wickham
authors.forename: Nicholas
authors.initials: N
authors.lastname: Regan
authors.forename: Matthew B
authors.initials: MB
authors.lastname: West
authors.forename: Justin
authors.initials: J
authors.lastname: Thai
authors.forename: Paul F
authors.initials: PF
authors.lastname: Cook
authors.forename: Simon S
authors.initials: SS
authors.lastname: Terzyan
authors.forename: Pui Kai
authors.initials: PK
authors.lastname: Li
authors.forename: Marie H
authors.initials: MH
authors.lastname: Hanigan
mesh_terms: D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects; D002478:Cells, Cultured; D015195:Drug Design; D004353:Drug Evaluation, Preclinical; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000378:metabolism / Q000494:pharmacology*; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D051379:Mice; D008954:Models, Biological; D041681:NIH 3T3 Cells; D011485:Protein Binding; D013379:Substrate Specificity; D013449:Sulfonamides / Q000494:pharmacology; D013830:Thiadiazoles / Q000494:pharmacology; D005723:gamma-Glutamyltransferase / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D000096926:Benzenesulfonamides
chemical_list: D004791:Enzyme Inhibitors; D005978:Glutathione; D013449:Sulfonamides; D013830:Thiadiazoles; D005723:gamma-Glutamyltransferase; C540802:N-(5-(4-methoxybenzyl)-1,3,4-thiadiazol-2-yl)benzenesulfonamide; D000096926:Benzenesulfonamides