1- sup 13 C; methyl-2H3 methionine kinetics in humans: Methionine conservation and cystine sparing

Journal Article · Tue May 01 04:00:00 EDT 1990 · American Journal of Physiology; (USA)

OSTI ID:7015994

Storch, K J; Wagner, D A; Burke, J F; Young, V R ^[1]

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1. Massachusetts Institute of Technology, Cambridge (USA)

Methionine (Met) conservation in healthy young adult men (4/diet group) was explored by supplying one of the following three L-amino acid based diets: (1) adequate Met but no cystine; (2) neither Met nor cystine; or (3) no Met but cystine supplementation. After 5 days, subjects received a continuous intravenous infusion of L-(1-13C; methyl-2H3)Met for 5 h while the diet was given as small isocaloric isonitrogenous meals. Estimates were made of rates of Met incorporation into protein synthesis (S) and release from body proteins (B), transmethylation (TM), remethylation of homocysteine (RM), and transsulfuration (TS). For the adequate Met diet, the rates were S = 24 +/- 2, B = 18 +/- 1, TM = 12.4 +/- 1.7, RM = 4.7 +/- 1.1, and TS = 7.6 +/- 0.6 (SE) mumol.kg-1.h-1. The sulfur amino acid-devoid diet significantly (P less than 0.05) reduced S, TM, RM, and TS. Supplementation of this diet with cystine reduced Met oxidation (P = 0.05). Therefore, two loci are quantitatively important regulatory points in Met conservation in vivo: (1) the distribution of Met between the pathways of protein anabolism and TM (Met locus) and (2) the distribution of homocysteine between RM and TS (homocysteine locus).

• OSTI ID: 7015994
• Journal Information: American Journal of Physiology; (USA), Journal Name: American Journal of Physiology; (USA) Vol. 258; ISSN 0002-9513; ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
ANABOLISM
ANIMALS
BIOLOGICAL PATHWAYS
CARBON 13
CARBON ISOTOPES
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
CYSTINE
DEUTERIUM
DIET
DISULFIDES
DRUGS
EVEN-ODD NUCLEI
HYDROGEN ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPE DILUTION
ISOTOPES
LABELLING
LIGHT NUCLEI
LIPOTROPIC FACTORS
MAMMALS
MAN
METABOLISM
METHIONINE
METHYLATION
NUCLEI
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PRIMATES
STABLE ISOTOPES
TRACER TECHNIQUES
VERTEBRATES