Influence of glucogenic amino acids on the hepatic metabolism of threonine

Moundras, Corinne; Bercovici, Daniel; Rémésy, Christian; Demigné, Christian

doi:10.1016/0304-4165(92)90056-z

Cited by 15 publications

(15 citation statements)

References 21 publications

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“…). Since the induction of threonine ammonia‐lyase is associated with an increase in the fractional hepatic extraction of Thr and a drop in circulating Thr in the bloodstream, our isotopic and physiological results indicate that there was increased oxidation of Thr by threonine ammonia‐lyase in HP vs. AP fed rats (Supplementary Fig. S3, Supporting Information).…”

Section: Discussionmentioning

confidence: 79%

The dietary protein paradox and threonine ¹⁵N‐depletion: Pyridoxal‐5'‐phosphate enzyme activity as a mechanism for the δ¹⁵N trophic level effect

Fuller

Petzke

2017

Rapid Comm Mass Spectrometry

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The N-depleted results of threonine are linked to increased activity of threonine ammonia-lyase, and show potential as a possible biomarker for protein intake and/or gluconeogenesis. We hypothesize that the inverse nitrogen equilibrium isotope effects of Schiff base formation, between AAs and pyridoxal-5'-phosphate cofactor enzymes, play a key role in the bioaccumulation and depletion of N in the biomolecules of living organisms and contributes to the variability in the nitrogen trophic level effect. Copyright © 2017 John Wiley & Sons, Ltd.

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Section: Discussionmentioning

confidence: 79%

The dietary protein paradox and threonine ¹⁵N‐depletion: Pyridoxal‐5'‐phosphate enzyme activity as a mechanism for the δ¹⁵N trophic level effect

Fuller

Petzke

2017

Rapid Comm Mass Spectrometry

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“…Human milk may contain a substance, such as a growth factor or a hormone, that enhances the activity of this enzyme and that is lacking in formula. In addition, the activity of this enzyme is influenced by the protein content of the diet (38) and can be induced not only by a high-protein diet (18) but also by the addition of certain glucogenic amino acids (39) and glutamic acid to the diet (40,41). Rats have been shown to respond to low-protein diets with reduced threonine dehydratase activity (38).…”

Section: Discussionmentioning

confidence: 99%

“…Hepatic threonine uptake into liver has been shown to be low compared with the uptake of other amino acids in pigs (45) and rats (46). Moundras et al (39) showed that the induction of threonine dehydratase was associated with an increase in the fractional hepatic extraction of threonine and a drop in circulating plasma threonine. Clearly, more research is needed to define the mechanism underlying the differences in threonine oxidation rates between formula-fed infants and those fed their mothers' milk.…”

Section: Discussionmentioning

confidence: 99%

Threonine kinetics in preterm infants fed their mothers' milk or formula with various ratios of whey to casein

Darling

Dunn

Sarwar

et al. 1999

The American Journal of Clinical Nutrition

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Background: Plasma threonine concentrations are elevated in infants fed formula containing a whey-to-casein protein ratio of 60:40 compared with concentrations in infants fed formula containing a ratio of 20:80 or human milk (60:40). Objective: We studied whether degradation of excess threonine was lower in formula-fed infants than in infants fed their mothers' milk. Design: Threonine kinetics were examined in 17 preterm infants (gestational age: 31 ± 2 wk; birth weight: 1720 ± 330 g) by using an 18-h oral infusion of [1-13 C]threonine at a postnatal age of 21 ± 11 d and weight of 1971 ± 270 g. Five infants received breast milk. Formula-fed infants (n = 12) were randomly assigned to receive 1 of 3 formulas (5.3 g protein/MJ) that differed only in the whey-to-casein ratio (20:80, 40:60, and 60:40). Results: Threonine intake increased significantly in formula-fed infants with increasing whey content of the formula (48.5, 56.4, and 63.2 mol · kg Ϫ1 · h Ϫ1 , respectively; pooled SD: 2.2; P = 0.0001), as did plasma threonine concentrations (228, 344, and 419 mol/L, respectively; pooled SD: 75; P = 0.03). Despite a generous threonine intake by infants fed breast milk (58.0 ± 16.0 mol · kg Ϫ1 · h Ϫ1 ), plasma threonine concentrations remained low (208 ± 41 mol/L). Fecal threonine excretion and net threonine tissue gain, estimated by nitrogen balance, did not differ significantly among groups. Threonine oxidation did not differ significantly among formula-fed infants but was significantly lower in formula-fed infants fed than in infants fed breast milk (17.1% compared with 24.3% of threonine intake, respectively). Conclusion: Formula-fed infants have a lower capacity to oxidize threonine than do infants fed breast milk.Am J Clin Nutr 1999;69:105-14.

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“…L-Threonine may be catabolised by threonine dehydratase (TDH) in the cytosol to NH 4 + and 2-ketobutyrate, which is rapidly and irreversibly converted to CO 2 , or it may be metabolised by threonine dehydrogenase (TDG) in the mitochondria to form 2-amino-3-ketobutyrate, which is then cleaved by 2-aminoketobutyrate CoA ligase to form glycine and acetyl-CoA (Dale, 1978;Bird and Nunn, 1983). The TDG pathway has been shown to account for 80 % of threonine disposal in growing pigs (Ballevre et al, 1990;le Floc'h et al, 1994) and rats (Bird and Nunn 1983;Moundras et al, 1992), making it the major degradative pathway, but it accounts for only 7-10 % of threonine disposal in humans (Darling et al, 2000). L-Threonine is among the amino acids most rapidly degraded by ruminal microorganisms, with an estimated half-life in the rumen of 1.1 hours (Chalupa, 1976).…”

Section: Conclusion and Recommendationsmentioning

confidence: 99%

Scientific opinion on the safety and efficacy of L‐threonine produced by Escherichia coli (FERM BP‐10942) for all animal species based on a dossier submitted by Ajinomoto Eurolysine SAS

Feed¹

2013

EFS2

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The product L-threonine, technically pure, is an essential amino acid that contains by specification ≥ 98 % Lthreonine. It is produced by a genetically modified Escherichia coli strain. Neither the production strain nor its recombinant DNA was detectable in the final product. The final product does not raise safety concerns with regard to the genetic modification. L-Threonine, technically pure, is considered safe for the target animals when used to meet the requirements. The toxicological studies, including mutagenicity tests, performed with the additive or other sources of L-threonine did not reveal any toxic effect. Since the composition of tissues and products of animal origin will not be changed by the use of L-threonine in animal nutrition, and considering the high purity of the product under assessment, no risks are expected for the consumer from the use of L-threonine, technically pure, as a feed additive. The product is not irritating to the skin or eyes and is not likely to be a skin sensitiser. Although there is a potential for user exposure by inhalation, there is no evidence of acute toxicity by the inhalation route. The use of the product as a feed additive does not represent a risk to the environment. LThreonine, technically pure, is considered as an efficacious source of L-threonine for all animal species. Response in ruminants requires some degree of protection of threonine from ruminal degradation. SUMMARYFollowing a request from the European Commission, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on the safety and efficacy of the product L-threonine, technically pure, for all animal species.Threonine is an essential amino acid, considered as the second limiting amino acid in pig feed and probably as the third limiting in poultry feed. Supplementing feedingstuffs with free threonine would ensure that the animal requirements for that amino acid are met.The product L-threonine, technically pure, contains by specification ≥ 98 % L-threonine. It is produced by a genetically modified Escherichia coli strain.Neither the production strain nor its recombinant DNA was detectable in the final product. The final product does not raise safety concerns with regard to the genetic modification.L-Threonine, technically pure, is considered safe for the target animals when used to meet the requirements.The toxicological studies, including mutagenicity tests, performed with the additive or other sources of L-threonine did not reveal any toxic effect. Since the composition of tissues and products of animal origin will not be changed by the use of L-threonine in animal nutrition, and considering the high purity of the product under assessment, no risks are expected for the consumer from the use of Lthreonine, technically pure, as a feed additive.The product is not irritating to the skin or eyes and is not likely to be a skin sensitiser. Although there is a potential for user exposure by inhalation, there is no evidence of acute tox...

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Influence of glucogenic amino acids on the hepatic metabolism of threonine

Cited by 15 publications

References 21 publications

The dietary protein paradox and threonine ¹⁵N‐depletion: Pyridoxal‐5'‐phosphate enzyme activity as a mechanism for the δ¹⁵N trophic level effect

The dietary protein paradox and threonine ¹⁵N‐depletion: Pyridoxal‐5'‐phosphate enzyme activity as a mechanism for the δ¹⁵N trophic level effect

Threonine kinetics in preterm infants fed their mothers' milk or formula with various ratios of whey to casein

Scientific opinion on the safety and efficacy of L‐threonine produced by Escherichia coli (FERM BP‐10942) for all animal species based on a dossier submitted by Ajinomoto Eurolysine SAS

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Influence of glucogenic amino acids on the hepatic metabolism of threonine

Cited by 15 publications

References 21 publications

The dietary protein paradox and threonine 15N‐depletion: Pyridoxal‐5'‐phosphate enzyme activity as a mechanism for the δ15N trophic level effect

The dietary protein paradox and threonine 15N‐depletion: Pyridoxal‐5'‐phosphate enzyme activity as a mechanism for the δ15N trophic level effect

Threonine kinetics in preterm infants fed their mothers' milk or formula with various ratios of whey to casein

Scientific opinion on the safety and efficacy of L‐threonine produced by Escherichia coli (FERM BP‐10942) for all animal species based on a dossier submitted by Ajinomoto Eurolysine SAS

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The dietary protein paradox and threonine ¹⁵N‐depletion: Pyridoxal‐5'‐phosphate enzyme activity as a mechanism for the δ¹⁵N trophic level effect

The dietary protein paradox and threonine ¹⁵N‐depletion: Pyridoxal‐5'‐phosphate enzyme activity as a mechanism for the δ¹⁵N trophic level effect