Methionine Sulphoximine and some Enzyme Systems involving Glutamine

Pace, J.; McDermott, E. E.

doi:10.1038/169415a0

Cited by 102 publications

(36 citation statements)

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“…Thus we analyzed ICDH activity and concentration in Prochlorococcus sp. PCC 9511 cultures after addition of 100 µM methionine sulfoximine (MSX, an specific inhibitor of GS [74]) and 100 µM azaserine (specific inhibitor of GOGAT [75]). The results are shown in Figs.…”

Section: Resultsmentioning

confidence: 99%

Physiological Regulation of Isocitrate Dehydrogenase and the Role of 2-Oxoglutarate in Prochlorococcus sp. Strain PCC 9511

et al. 2014

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The enzyme isocitrate dehydrogenase (ICDH; EC 1.1.1.42) catalyzes the oxidative decarboxylation of isocitrate, to produce 2-oxoglutarate. The incompleteness of the tricarboxylic acids cycle in marine cyanobacteria confers a special importance to isocitrate dehydrogenase in the C/N balance, since 2-oxoglutarate can only be metabolized through the glutamine synthetase/glutamate synthase pathway. The physiological regulation of isocitrate dehydrogenase was studied in cultures of Prochlorococcus sp. strain PCC 9511, by measuring enzyme activity and concentration using the NADPH production assay and Western blotting, respectively. The enzyme activity showed little changes under nitrogen or phosphorus starvation, or upon addition of the inhibitors DCMU, DBMIB and MSX. Azaserine, an inhibitor of glutamate synthase, induced clear increases in the isocitrate dehydrogenase activity and icd gene expression after 24 h, and also in the 2-oxoglutarate concentration. Iron starvation had the most significant effect, inducing a complete loss of isocitrate dehydrogenase activity, possibly mediated by a process of oxidative inactivation, while its concentration was unaffected. Our results suggest that isocitrate dehydrogenase responds to changes in the intracellular concentration of 2-oxoglutarate and to the redox status of the cells in Prochlorococcus.

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Section: Resultsmentioning

confidence: 99%

Physiological Regulation of Isocitrate Dehydrogenase and the Role of 2-Oxoglutarate in Prochlorococcus sp. Strain PCC 9511

et al. 2014

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“…M.S.O. is a specific and irreversible inhibitor ofglutamine synthetase (Pace and McDermott, 1952;Larnar and Sellinger, 1965). This enzyme is important for the conversion of glutamate and Fig.…”

Section: Discussionmentioning

confidence: 98%

An ultrastructural study of methionine sulphoximine-induced glycogen accumulation in astrocytes of the mouse cerebral cortex

Phelps

1975

J Neurocytol

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Glycogen distribution in the mouse cerebral cortex was examined with electron microscopy following treatment with the experimental convulsant, methionine sulphoximine (M.S.O.). Both at 24 and 48 h followed administration of M.S.O., accumulation of particulate glycogen was prominent in astrocytes throughout the cerebral cortex. In astrocyte cell bodies and in subpial, pericapillary and perineuronal astrocyte processes the glycogen often completely filled the cytoplasm, crowding the remaining organelles and inclusions. The present findings correlate well with biochemical studies of M.S.O. effects of glutamine synthetase activity and energy metabolism. It is suggested that the glycogen may be derived from glutamate which under normal conditions would be converted to glutamine.

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“…I-Methionine-DLsulfoximine (MSX), an analogue of glutamate, the substrate of GS, is a powerful inhibitor of GS (Pace and McDermott, 1952;Syrett, 1981). Numerous studies have used MSX inhibition to confirm that GS rather than GDH was the primary ammonium assimilatory pathway in bacteria (Brenchley, 1973;Moreno-Vivian et aI., 1983), cyanobacteria (Flores et aI., 1980;Boussiba and Gibson, 1985), and eucaryotic algae (Cresswell and Syrett, 1984;Rigano et al, 1979).…”

Section: Assimilatory Pathwaysmentioning

confidence: 99%