epsilon-N-trimethyllysine availability regulates the rate of carnitine biosynthesis in the growing rat
Rates of carnitine biosynthesis in mammals depend on the availability of substrates and the activity of enzymes subserving the pathway. This study was undertaken to test the hypothesis that the availability of epsilon-N-trimethyllysine is rate-limiting for synthesis of carnitine in the growing rat and to evaluate diet as a source of this precursor for carnitine biosynthesis. Rats apparently absorbed greater than 90% of a tracer dose of (methyl-/sup 3/H)epsilon-N-trimethyllysine, and approximately 30% of that was incorporated into tissues as (/sup 3/H)carnitine. Rats given oral supplements of epsilon-N-trimethyllysine (0.5-20 mg/d), but no dietary carnitine, excreted more carnitine than control animals receiving no dietary epsilon-N-trimethyllysine or carnitine. Rates of carnitine excretion increased in a dose-dependent manner. Tissue and serum levels of carnitine also increased with dietary epsilon-N-trimethyllysine supplementation. There was no evidence that the capacity for carnitine biosynthesis was saturated even at the highest level of oral epsilon-N-trimethyllysine supplementation. Common dietary proteins (casein, soy protein and wheat gluten) were found to be poor sources of epsilon-N-trimethyllysine for carnitine biosynthesis. The results of this study indicate that the availability of epsilon-N-trimethyllysine limits the rate of carnitine biosynthesis in the growing rat.
- Research Organization:
- Univ. of Iowa College of Medicine, Iowa City
- OSTI ID:
- 5429984
- Journal Information:
- J. Nutr.; (United States), Vol. 5
- Country of Publication:
- United States
- Language:
- English
Similar Records
Kinetic compartmental analysis of carnitine metabolism in the human carnitine deficiency syndromes. Evidence for alterations in tissue carnitine transport
Protein quality and quantity and insulin control of mammary gland glucose utilization during lactation
Related Subjects
CARNITINE
BIOSYNTHESIS
EXCRETION
HYDROXYLASES
ENZYME ACTIVITY
LYSINE
BIOLOGICAL AVAILABILITY
BIOLOGICAL PATHWAYS
DIET
DOSE-RESPONSE RELATIONSHIPS
PRECURSOR
RATS
TISSUE DISTRIBUTION
TRACER TECHNIQUES
TRITIUM COMPOUNDS
AMINO ACIDS
ANIMALS
CARBOXYLIC ACIDS
CLEARANCE
DISTRIBUTION
ENZYMES
HYDROXY ACIDS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MAMMALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDOREDUCTASES
RODENTS
SYNTHESIS
VERTEBRATES
VITAMIN B GROUP
VITAMINS
550201* - Biochemistry- Tracer Techniques