A radioisotope assay for L-glutaminase: the measurement of tritiated water formation from the reaction of L-[2-3H]glutamine with the L-glutaminase and glutamate oxalacetate transaminase couple.

  title={A radioisotope assay for L-glutaminase: the measurement of tritiated water formation from the reaction of L-[2-3H]glutamine with the L-glutaminase and glutamate oxalacetate transaminase couple.},
  author={C. Zielke and H. R. Zielke and P. Ozand},
  journal={Analytical biochemistry},
  volume={127 1},
Abstract An assay for the determination of l -glutaminase in extracts and intact cells is described. The method is based on the stereospecific release of 3 H 2 O from l -[2- 3 H]glutamine when l -glutaminase is coupled to l -aspartate:2-oxoglutarate amino transferase. The substrate, glutamine, and intermediate product, glutamate, are separated from the final reaction product, tritiated water, on a mixed-bed ion-exchange column which retains amino acids and organic acids but not water. The… Expand
Functional intracellular glutaminase activity in intact astrocytes
Evidence is provided that phosphate-activated glutaminase activity in vivo is regulated by cellular metabolites, that its “functional” activity is 5–9% of the rate obtained using extracts, and this ‘functional’ activity is sufficient to account for the rate of glutamine oxidation. Expand
Glutamine Metabolism by Cultured Mammalian Cells
Cultured mammalian cells are grown in medium containing carbohydrates, amino acids, salts, vitamins, and growth factors. In the 1950’s Eagle [1] identified the basic composition of tissue cultureExpand
Characterization of glutamine metabolism in two related murine hybridomas.
The relative enzyme activities and the amount of ammonia produced during growth indicated that glutamine is oxidized preferentially via the transamination pathway and suggests that transport may regulate glutamine metabolism. Expand


Radioisotope assay for glutamine synthetase using thinlayer chromatography
Abstract A simple radiochemical method for the determination of glutamine synthetase activity by thin-layer chromatography is described. The assay involves the separation of glutamine from glutamicExpand
A new method for the assay of glutaminase activity: direct measurement of product formation by an ammonia electrode.
  • Y. Huang
  • Chemistry, Medicine
  • Analytical biochemistry
  • 1974
The concentrations of the three glutaminase isoenzymes from rat tissues measured by this method are strictly comparable to those measured by other methods. Expand
Labilization of the α-Hydrogen of Amino-acids in the Presence of Aminopherase
IT has been shown previously in experiments with crude glutamic aminopherase, α-deuterio-alanine and α-ketoglutarate that enzymatic transamination involves dissociation of the α-hydrogen of theExpand
The distribution of glutaminase isoenzymes in the various structures of the nephron in normal, acidotic, and alkalotic rat kidney.
Only the phosphate-dependent glutaminase activity responds to metabolic acidosis or alkalosis and this response appears to be limited to the proximal convoluted tubules, whereas after administration of NH4Cl for 7 days to induce acidosis the activity increased 20-fold, whereas 7 days of NaHCO3 administration to induce alkAlosis caused a 40% decrease. Expand
Glutaminase from pig renal cortex. I. Purification and general properties.
The Tris-HCl enzyme has a pH optimum of about pH 9, whereas no distinct optimum in the pH range 8 to 9 has been shown for the phosphate-borate enzyme, which suggests allosteric properties. Expand
The intramitochondrial location of the glutaminase isoenzymes of pig kidney.
It is concluded that both glutaminases isoenzymes are situated in the intramitochondrial compartment, and that the phosphate-independent glutaminase may be bound to the inside of the inner mitochondrial membrane. Expand
Activities of enzymes required for the conversion of 4-carbon TCA cycle compounds to 3-carbon glycolytic compounds in human diploid fibroblasts.
The results support an active conversion of 4-carbon tricarboxylic acid cycle intermediates to 3-carbon glycolytic intermediates in HDF and specific activities of mitochondrial PEPCK and cytosolic malic enzyme, MDH and GOT increased during cell growth. Expand
NADH-Dependent coupled enzyme assay for urease and other ammonia-producing systems.
A coupled optical enzyme assay for urease was developed that depends on the requirement of equimolar amounts of NADH and ammonia for glutamic acid synthesis, determined spectrophotometrically. Expand
Increase in glutaminase activity during the growth cycle of cultured human diploid fibroblasts.
Results indicate that glutaminase, the first enzyme involved in the ultilization of glutamine as an energy source, is elevated in rapidly dividing human diploid fibroblasts. Expand
Comparison of the oxidation of glutamine, glucose, ketone bodies and fatty acids by human diploid fibroblasts.
These cells meet their energy requirement almost solely by anaerobic glycolysis and glutamine oxidation, and the other substrates had no effect. Expand