GLUTATHIONE, BUT NOT GLUTAMINE, IS DETECTED IN C-13-NMR SPECTRA OF PERCHLORIC-ACID EXTRACTS FROM C6 GLIOMA-CELLS

Glutamine, which is expected to be produced by C6 glioma cells, is not detected in both amino-acid analyses and C-13-NMR spectra of perchlor ic acid extracts of cells incubated for 4 h with 1-C-13!glucose in th e absence of extracellular glutamine. However, the resonances of a glu tamate-linked product are observed in these spectra. The analysis of t he pH dependence of chemical shifts from various glutamate-derived com pounds shows that the observed resonances came from glutathione. Gluta mine and glutathione signals are in close proximity on the frequency s cale, leading to possible misinterpretation of the spectra.