Document Detail

Quantitative aspects of glycine and alanine nitrogen metabolism in postabsorptive young men: effects of level of nitrogen and dispensable amino acid intake.
MedLine Citation:
PMID:  3973749     Owner:  NLM     Status:  MEDLINE    
The nutritionally indispensable amino acids (IAA) alone do not maintain body nitrogen (N) balance; a source of "nonspecific" nitrogen from dispensable amino acids (DAA), such as from glycine and alanine or other N compounds, is required. However, the in vivo regulation of the metabolism of these amino acids in humans with varying nutritional states has received little study. Hence, the effects of N intake and the IAA:DAA ratio on kinetic aspects of whole-body alanine and glycine metabolism were examined in eight healthy young adult male subjects. They received an L-amino acid diet supplying N equivalent to about 1.5 g and 0.6 g protein (N X 6.25) per kilogram body weight per day. All were studies at each N level with the IAA:DAA ratio (wt/wt) of 1:1 and 1:0, each for a 7-d diet period. Constant primed, intravenous infusions of L-[1-13C]leucine together with either L-[15N]alanine (four subjects) or [15N]glycine (four subjects) were given to each subject at the end of the diet period, after an overnight fast, to determine rates of de novo whole-body alanine and glycine N synthesis. The rate of alanine synthesis was similar (P greater than 0.05) for all four diets. Glycine de novo N synthesis declined (P less than 0.01) with removal of dietary DAA, especially at the lower intake, where the mean rates [micromoles/(kilogram X hour)] were 59 and 20 for 1:1 and 1:0 ratios, respectively. The possible significance of reduced rates of glycine N synthesis for maintenance of protein nutritional status in the healthy adult is discussed.
Y M Yu; R D Yang; D E Matthews; Z M Wen; J F Burke; D M Bier; V R Young
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of nutrition     Volume:  115     ISSN:  0022-3166     ISO Abbreviation:  J. Nutr.     Publication Date:  1985 Mar 
Date Detail:
Created Date:  1985-04-18     Completed Date:  1985-04-18     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0404243     Medline TA:  J Nutr     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  399-410     Citation Subset:  IM    
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MeSH Terms
Alanine / biosynthesis*
Amino Acids / administration & dosage*,  blood
Amino Acids, Essential / administration & dosage
Dietary Proteins / administration & dosage
Glycine / biosynthesis*
Models, Biological
Nitrogen / administration & dosage*,  blood
Grant Support
Reg. No./Substance:
0/Amino Acids; 0/Amino Acids, Essential; 0/Dietary Proteins; 56-40-6/Glycine; 56-41-7/Alanine; 7727-37-9/Nitrogen

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