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Updated: Jul 18, 2026

Glutamine Flux Imaging Using Genetically Encoded Sensors
Published on: July 31, 2014
Reversible inhibition of mammalian glutamine synthetase by tyrosine nitration
Boris Görg1, Natalia Qvartskhava, Peter Voss
1Clinic for Gastroenterology, Hepatology and Infectiology, Heinrich-Heine-University Düsseldorf, Moorenstrasse 5, D-40225 Dusseldorf, Germany.
Abstract:
The effect of tyrosine nitration on mammalian GS activity and stability was studied in vitro. Peroxynitrite at a concentration of 5 micro mol/l produced tyrosine nitration and inactivation of GS, whereas 50 micro mol/l peroxynitrite additionally increased S-nitrosylation and carbonylation and degradation of GS by the 20S proteasome. (-)Epicatechin completely prevented both, tyrosine nitration and inactivation of GS by peroxynitrite (5 micro mol/l). Further, a putative "denitrase" activity restored the activity of peroxynitrite (5 micro mol/l)-treated GS. The data point to a potential regulation of GS activity by a reversible tyrosine nitration. High levels of oxidative stress may irreversibly damage and predispose the enzyme to proteasomal degradation.
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