Conversion of gamma-glutamylcysteinylethyl ester to glutathione in rat hepatocytes.
The conversion of gamma-glutamylcysteinylethyl ester (gamma-GCE) to glutathione in a reduced form (GSH) was examined using isolated rat hepatocytes pretreated with diethylmaleate, a GSH-depletor. Incubation of hepatocytes with 0.1 and 5.0 mM gamma-GCE (gamma-GCE-hepatocytes) over a 30-min period resulted in time-dependent increases in intracellular GSH and nonprotein-SH (NP-SH) concentrations. Hepatocytes incubated with 5.0 mM but not 0.1 mM GSH over a period of 30 min showed a time-dependent increase in intracellular GSH concentration. In the gamma-GCE-hepatocytes pretreated with bis-(p-nitrophenyl)phosphate (BNPP), a non-specific esterase inhibitor, an enhancement of intracellular GSH concentration was markedly reduced. gamma-GCE concentration in the gamma-GCE-hepatocytes with BNPP pretreatment was significantly higher than that in the cells without BNPP pretreatment, although there was no difference in the total amount of intracellular NP-SH, i.e., gamma-GCE, GSH, gamma-glutamylcysteine, cysteine ethyl ester, and cysteine between both gamma-GCE-hepatocytes. The present results indicate that gamma-GCE is transported into liver cells more easily than GSH itself, resulting in its conversion to GSH via esterase and glutathione synthetase within the cells.
Nishida
K
K
Department of Biochemistry, School of Medicine, Fujita Health University, Aichi, Japan.
Ohta
Y
Y
Ito
M
M
Nagamura
Y
Y
Kitahara
S
S
Fujii
K
K
Ishiguro
I
I
D000818:Animals; D001692:Biological Transport; D004151:Dipeptides / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism*; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008297:Male; D008298:Maleates / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013438:Sulfhydryl Compounds / Q000378:metabolism
D004151:Dipeptides; D008298:Maleates; D013438:Sulfhydryl Compounds; C067744:N-gamma-glutamylcysteine ethyl ester; D007770:L-Lactate Dehydrogenase; C014476:diethyl maleate; D005978:Glutathione