Factors influencing pyrroline 5-carboxylate synthesis from glutamate by rat intestinal mucosa mitochondria
Factors influencing pyrroline 5-carboxylate (P5C) synthesis from glutamate by a subcellular fraction enriched in mitochondria of rat small intestinal mucosa have been studied. P5C synthesis decreased rapidly if this subcellular fraction was preincubated at 20 degrees C in the absence of substrates; this effect suggests that the enzyme(s) catalyzing P5C synthesis from glutamate (P5C synthase) is unstable in the absence of substrates. In the presence of substrates P5C synthesis increased linearly for the first 30 min of incubation, suggesting that the substrates promote enzyme stability. Pyridoxal 5'-phosphate is an effective inhibitor of P5C synthase whereas pyridoxamine 5'-phosphate and pyridoxal are not inhibitory. Potassium phosphate, KCl, and KBr each inhibited P5C synthase but potassium-Hepes (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) did not. Potassium phosphate was the most potent inhibitor followed by KBr, and then KCl. These results suggest P5C synthase is sensitive to anion inhibition. Both L-ornithine and D-ornithine inhibited P5C synthase; L-proline did not inhibit. Several analogs of ornithine and proline were also tested and none was found to inhibit P5C synthase; the inhibition by ornithine is, therefore, rather specific and it may prove to contribute to the regulation of metabolism of these amino acids.
- Research Organization:
- Univ. of North Carolina, Chapel Hill
- OSTI ID:
- 5022491
- Journal Information:
- Arch. Biochem. Biophys.; (United States), Vol. 226:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ENZYME ACTIVITY
INHIBITION
GLUTAMIC ACID
METABOLISM
ORNITHINE
OXIDOREDUCTASES
BIOCHEMICAL REACTION KINETICS
PROLINE
BIOSYNTHESIS
MITOCHONDRIA
MUCOUS MEMBRANES
RATS
SMALL INTESTINE
AMINES
AMINO ACIDS
ANIMALS
AZOLES
BODY
CARBOXYLIC ACIDS
CELL CONSTITUENTS
DIGESTIVE SYSTEM
ENZYMES
GASTROINTESTINAL TRACT
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INTESTINES
KINETICS
MAMMALS
MEMBRANES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANOIDS
ORGANS
PYRROLES
PYRROLIDINES
REACTION KINETICS
RODENTS
SYNTHESIS
VERTEBRATES
550200* - Biochemistry