| Glutamine metabolism and function in relation to proline synthesis and the safety of glutamine and proline supplementation. | |
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MedLine Citation:
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PMID: 18806115 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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At normal intakes, dietary glutamine and glutamate are metabolized by the small intestine and essentially all glutamine within the body is synthesized de novo through the action of glutamine synthetase. The major sites of net glutamine synthesis are skeletal muscle, lung, and adipose tissue and, under some conditions, the liver. In addition to the small intestine, where glutamine is the major respiratory fuel, other sites of net glutamine utilization include the cells of the immune system, the kidneys, and the liver. The intestine expresses pyrroline 5-carboxylate (P5C) synthase, which means that proline is an end product of intestinal glutamine catabolism. Proline can also be synthesized from ornithine and the exact contribution of the 2 pathways is not certain. Infusion of proline i.v. to increase circulating concentrations is associated with increased proline oxidation and decreased proline synthesis. In contrast, conditions of proline insufficiency, after feeding low-proline diets or in response to high rates of proline catabolism in burn patients, do not result in increased proline synthesis. Glutamine supplementation is widespread and up to 0.57-0.75 g.kg(-1).d(-1) is well tolerated. Similarly, the only study of proline supplementation, in which patients with gyrate atrophy were given 488 mg.kg(-1).d(-1), reported no deleterious side effects. In the absence of controlled trials, it is currently not possible to estimate a safe upper limit for either of these 2 amino acids. |
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Authors:
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Malcolm Watford |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: The Journal of nutrition Volume: 138 ISSN: 1541-6100 ISO Abbreviation: J. Nutr. Publication Date: 2008 Oct |
Date Detail:
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Created Date: 2008-09-22 Completed Date: 2008-12-02 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0404243 Medline TA: J Nutr Country: United States |
Other Details:
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Languages: eng Pagination: 2003S-2007S Citation Subset: IM |
Affiliation:
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Department of Nutritional Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA. watford@aesop.rutgers.edu |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Biotransformation Chickens Dietary Supplements* Glutamate-Ammonia Ligase / metabolism Glutamine / administration & dosage*, metabolism* Humans Ornithine / metabolism Proline / administration & dosage*, biosynthesis* Pyrroline Carboxylate Reductases / metabolism Safety Species Specificity Swine |
| Grant Support | |
ID/Acronym/Agency:
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DK073515/DK/NIDDK NIH HHS |
| Chemical | |
Reg. No./Substance:
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147-85-3/Proline; 56-85-9/Glutamine; 7006-33-9/Ornithine; EC 1.5.1.-/Pyrroline Carboxylate Reductases; EC 1.5.1.2/delta-1-pyrroline-5-carboxylate reductase; EC 6.3.1.2/Glutamate-Ammonia Ligase |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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