PMID: 1546970Mar 1, 1992Paper

Glutamine catabolism by heart muscle. Properties of phosphate-activated glutaminase

The Biochemical Journal
D NelsonM Erecińska

Abstract

1. Rat heart homogenates catabolized glutamine in the presence of rotenone, an inhibitor of the respiratory chain. 2. The reaction was markedly stimulated by phosphate and inhibited by glutamate, but not greatly affected by ammonia. 3. Glutamine breakdown was enhanced by lactate, malate, citrate and ATP, and almost completely blocked by 1 mM-N-ethylmaleimide. 4. The Km for glutamine measured in homogenates supplemented with either 50 mM- or 100 mM-phosphate and at pH 7.3 or 8.0 was about 4 mM, whereas the Vmax was larger at higher anion concentrations and at the more alkaline pH. 5. Activity of glutaminase was 3-fold greater in isolated mitochondria than in muscle homogenates. Distribution of the activity was the same as that of a mitochondrial marker, cytochrome c oxidase. 6. Properties of glutaminase with respect to its dependence on the concentrations of phosphate, glutamine and H+ were the same in intact and broken mitochondria and very similar to those in homogenates. However, the specific activity of the enzyme was considerably smaller in frozen-thawed than in intact organelles. 7. It is concluded that heart mitochondria possess a kidney-type phosphate-activated glutaminase that can serve as a source of myocardial glutamate.

Citations

Feb 15, 2002·Nutrition·S E KhogaliM J Rennie
Feb 16, 2013·Neurochemical Research·Jason R TrebergDirk Weihrauch
Jun 24, 2010·The Biochemical Journal·Zvezdana Popovic, Douglas M Templeton
Aug 3, 2010·Liver International : Official Journal of the International Association for the Study of the Liver·Gavin WrightRajiv Jalan
Oct 1, 1993·Hepatology : Official Journal of the American Association for the Study of Liver Diseases·Cornelis H C DejongPeter B Soeters
Jan 5, 2000·American Journal of Respiratory and Critical Care Medicine·M P EngelenE F Wouters
Jul 18, 2014·Expert Opinion on Pharmacotherapy·Anna HadjihambiRajiv Jalan
Aug 29, 2003·American Journal of Physiology. Endocrinology and Metabolism·David M CohenHeinrich Taegtmeyer
Jan 12, 2002·FEMS Microbiology Letters·Marcus KleinThomas Jahns
Jan 1, 1996·Scandinavian Journal of Gastroenterology. Supplement·Cornelis H C DejongPeter B Soeters
Dec 11, 2008·Metabolic Brain Disease·Steven W M Olde DaminkCornelius H C Dejong
Jan 14, 1999·The American Journal of Physiology·W L RumseyM Erecińska
Oct 27, 1998·Comparative Biochemistry and Physiology. Part B, Biochemistry & Molecular Biology·G WuM Watford

Related Concepts

Anions
Calcium
Cations, Divalent
Enzyme Activation
Phosphate-Activated Glutaminase
D-Glutamine
Hydrogen-Ion Concentration
Mitochondria, Heart
Orthophosphate

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