Glutamine: fructose-6-phosphate amidotransferase

Fructose-6-phosphate + Glutamine <=> Glucosamine-6-Phosphate + Glutamate (catalyzed by Glutamine Fructose-6-Phosphate Amidotransferase)... 

Yki-Jarvinen, H. Vogt, C. Lozzo, P. Pipek, R. Daniels, M.C. Virkamaki, A. Makimattila, S. Mandarine, L. DeFronzo, R.A. McClain, D. Gottschalk, W.K. UDP-N-acetylglucosamine transferase and glutamine Fructose 6-phosphate amidotransferase activities in insulin-sensitive tissues. Diabetologia 1997, 40, 76-81. 

E.D. Crook, J. Zhou, M. Daniels, J.L. Neidigh and D.A. McClain, Diabetes, 1995, 44, 314-320, Regulation of glycogen synthase by glucose, glucosamine, and glutamine fructose-6-phosphate amidotransferase. 

R.R. Traxinger and S. Marshall, J. Biol. Chem., 1991, 266, 10148 10154, Coordinated Regulation of Glutamine Fructose-6-Phosphate Amidotransferase Activity by Insulin, Glucose, and Glutamine Role of Hexosamine Biosynthesis in Enzyme Regulation. 

In several studies of the L-glutamine D-fructose 6-phosphate amidotransferase reaction it has been shown that specific glutamine antagonists may be used to inhibit the reaction. Ghosh et al. (1960) showed that 6-diazo-5-oxo-L-norleucine (DON) was a potent inhibitor of the enzyme, whereas azaserine was less effective. The glutamine analogs, methionine sulfoxide and y-glutamyl hydrazide, on the other hand, were not inhibitory (Clarke and Pasternak, 1962). 

The glutamine analog 6-diazo-5-oxo-L-norleucine (DON) inhibits L-glu-tamine n-fructose-6-phosphate amidotransferase (Section III) in the-pathway of conversion of C-glucose to both sialic acid and N-acetylga-lactosamine and, as expected, thereby inhibits incorporation of C-glu-cose into OSM. With glucose as the sole carbohydrate source in the incubation medium, DON also inhibits incorporation of radioactive amino acids into OSM but causes a concomitant increased incorporation of labeled amino acid into other protein fractions these latter proteins may contain nonglycosylated polypeptide precursors of OSM. All the inhibitory effects of DON are prevented if glucosamine is present in the incul ition medium. 

Kornfeld, R., 1967, Studies on L-glutamine D-fructose 6-phosphate amidotransferase I. Feedback inhibition by uridine diphosphate-N-acetylglucosamine, J, Biol. Chem. 242 3135-3141. 

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