Ornithine synthesis from glutamate in rat small intestinal mucosa

Henslee, Jerry G.; Jones, Mary Ellen

doi:10.1016/0003-9861(82)90148-5

Cited by 29 publications

(14 citation statements)

References 42 publications

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“…In the present study, the plant protein OAT was expressed in E. coli, partially purified and its activity was estimated in presence of different amino acids. In earlier studies with rat liver and kidney, PLP stimulated ornithine synthesis and OAT activity [9]. Omission of PLP reduced the specific activity of OAT by 60% in the present study, thus confirming the earlier studies carried in animals.…”

Section: Discussionsupporting

confidence: 95%

Biochemical characterization, homology modeling and docking studies of ornithine δ-aminotransferase—an important enzyme in proline biosynthesis of plants

Sekhar

Amrutha

Sangam

et al. 2007

Journal of Molecular Graphics and Modelling

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Section: Discussionsupporting

confidence: 95%

Biochemical characterization, homology modeling and docking studies of ornithine δ-aminotransferase—an important enzyme in proline biosynthesis of plants

Sekhar

Amrutha

Sangam

et al. 2007

Journal of Molecular Graphics and Modelling

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“…Although enterocytes are equipped with enzymatic machinery for ornithine production from glutamate [14], the production of ornithine from L -[U- 14 C] glutamate was found to be very low, as previously reported in intestinal absorptive cells, the main precursor of ornithine being arginine [12]. This is in accordance with a previous study [34]showing that gut ornithine and arginine production is not altered by dietary glutamate.…”

Section: Discussionsupporting

confidence: 80%

“…Both glutamine and glutamate are metabolized in the intestine [8, 9]. Glutamine is considered as a fuel in intestinal absorptive cells and leads to the production of various metabolites including glutamate, ammonia, alanine [10, 11], aspartate [12], ornithine, citrulline and proline [13, 14, 15], glutathione [16, 17]and N-acetyl-glutamate [18]. Convincing evidence has been presented in favor of a complete metabolism of glutamate after a meal by the splanchnic bed [19, 20, 21].…”

Section: Introductionmentioning

confidence: 99%

Portal Hyperglutamatemia after Dietary Supplementation with Monosodium Glutamate in Pigs

Blachier

Vaugelade

et al. 1999

Digestion

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The aim of the present work was to examine in pigs the effect of a dietary supplementation with the flavor enhancer monosodium glutamate (MSG) on intestinal amino acid metabolism. For this purpose, pigs weighing 60 ± 2 kg received a standard meal twice a day for 1 week, supplemented with either 10 g MSG per meal or, as control experiments, an isonitrogenous amount of glycine together with an equal amount of sodium in the form of NaCl, the animals being their own control in all experiments. At the end of this period, pigs received a MSG or glycine-NaCl-supplemented meal and samples of portal and arterial blood were collected for amino acid analysis in plasma. The results demonstrate after MSG supplementation rapid significant increases in glutamate concentration in the portal and arterial blood plasma after a test meal which resulted in a positive portoarterial difference. In comparison, after glycine-NaCl supplementation, glutamate concentrations were almost identical in portal and arterial plasma. Furthermore, significant increased aspartate concentration in the portal blood plasma was observed after MSG supplementation when compared with control experiments. When enterocytes were isolated at the end of the supplementation period from the jejunum and examined for their metabolic capacities towards L-glutamate and L-glutamine, it was found that metabolism did not differ according to the supplement used, with glutamate and glutamine being oxidized and transaminated at a similar level. It is concluded that the portal hyperglutamatemia observed shortly after the ingestion of a MSG- supplemented meal is likely due to the saturation of the intestinal capacity to metabolize glutamate with no measurable adaptation of the metabolic pathways controlling glutamate metabolism in enterocytes.

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“…Windmueller and Spaeth (1 488 1) demonstrated that some of the ghtamine that is metabolized by the small intestine is converted to citmlline. The enzymology of this process has been clarified by Jones and her associates (Henslee andJones 1982: Wakabayashi andJones 1983). Glutamine is converted to glutamate by glutaminase, followed by phosphorylation to yglratarnyl phosphate, reduction to y-glutamyl semialdehyde (both steps probably catalyzed by pyrroline-5-carboxylate synthase), and transamination by omithine aminotransferase to omithine.…”

Section: Gitrulline and Argininementioning

confidence: 98%

The 1986 Borden Award Lecture. The role of the kidney in amino acid metabolism and nutrition

Brosnan¹

1987

Can. J. Physiol. Pharmacol.

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Measurement of the arteriovenous differences for free amino acids across rat kidney reveals that glycine and citrulline are removed and serine and arginine are added to the circulation. In addition, glutamine is taken up in large quantities by kidneys of animals that need to excrete large quantities of acid (e.g., diabetic animals, NH4Cl-fed animals, and animals fed a high protein diet). Glutamine is the major precursor of urinary ammonia and thus renal glutamine metabolism plays a key role in acid-base homeostasis. This process occurs primarily in the cells of the convoluted proximal tubule. Glutamine carbon is converted to glucose in acidotic rats and is totally oxidized in dogs. Regulation of glutamine metabolism occurs at two levels: acute regulation and chronic regulation. Acute regulation is, in part, mediated through a fall in intracellular [H+]. This activates alpha-ketoglutarate dehydrogenase and, ultimately, glutaminase. Chronic regulation involves induction of key enzymes, including, in the rat, glutaminase, glutamate dehydrogenase, and phosphoenolpyruvate carboxykinase. During the acidosis of prolonged starvation, the kidneys' requirement for glutamine must be met from muscle proteolysis and thus becomes a drain on lean body mass. Serine synthesis occurs by two separate pathways: from glycine by the combined actions of the glycine cleavage enzyme and serine hydroxymethyltransferase and from gluconeogenic precursors using the phosphorylated-intermediate pathway. Both pathways are located in the cells of the proximal tubule. Conversion of glycine to serine is ammoniagenic and the activity of the glycine cleavage enzyme is increased in acidosis. The function of serine synthesis by the phosphorylated-intermediate pathway is not apparent.(ABSTRACT TRUNCATED AT 250 WORDS)

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Ornithine synthesis from glutamate in rat small intestinal mucosa

Cited by 29 publications

References 42 publications

Biochemical characterization, homology modeling and docking studies of ornithine δ-aminotransferase—an important enzyme in proline biosynthesis of plants

Biochemical characterization, homology modeling and docking studies of ornithine δ-aminotransferase—an important enzyme in proline biosynthesis of plants

Portal Hyperglutamatemia after Dietary Supplementation with Monosodium Glutamate in Pigs

The 1986 Borden Award Lecture. The role of the kidney in amino acid metabolism and nutrition

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