Metabolism of excess methionine in the liver of intact rat: an in vivo /sup 2/H NMR study

Journal Article · Tue Nov 03 00:00:00 EST 1987 · Biochemistry; (United States)

OSTI ID:5599672

London, R E; Gabel, S A; Funk, A

L-Methionine is the most toxic amino acid if supplied in excess, and the metabolic basis for this toxicity has been extensively studied, with varying conclusions. It is demonstrated here that in vivo /sup 2/H NMR spectroscopy provides a useful approach to the study of the hepatic metabolism of methionine in the anesthetized rat. Resonances corresponding to administered L-(methyl-/sup 2/H/sub 3/)methionine, and to the transmethylation product sarcosine, are observed during the first 10-min period after an intravenous injection of the labeled methionine, and the time dependence has been followed for a period of 5 h. A third resonance, assigned to the N-trimethyl groups of carnitine, phosphorylcholine, and other metabolites, becomes observable several hours after administration of the deuteriated methionine. In addition, there is a small increase in the intensity of the HDO resonance over the period of the study, which is interpreted to reflect the ultimate oxidation of the labeled sarcosine methyl group via mitochondrial sarcosine dehydrogenase. Additional small /sup 2/H resonances assigned to N/sup 1/-methylhistidine and creatine could be observed in perchloric acid extracts of the livers of rats treated with the deuteriated methionine. Inhibition of the flux through the transmethylation pathway is observed in the rat pretreated with the S-ethyl analogue of methionine, ethionine. These data provide strong support for the importance of glycine transmethylation in the catabolism of excess methionine.

• Research Organization: National Institute of Environmental Health Sciences, Research Triangle Park, NC
• OSTI ID: 5599672
• Journal Information: Biochemistry; (United States), Vol. 26:22
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
LABELLED COMPOUNDS
METABOLISM
LIVER
NUCLEAR MAGNETIC RESONANCE
METHIONINE
DEUTERIUM COMPOUNDS
IN VIVO
INHIBITION
NMR SPECTRA
RATS
AMINO ACIDS
ANIMALS
BODY
CARBOXYLIC ACIDS
DIGESTIVE SYSTEM
DRUGS
GLANDS
HYDROGEN COMPOUNDS
LIPOTROPIC FACTORS
MAGNETIC RESONANCE
MAMMALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
ORGANS
RESONANCE
RODENTS
SPECTRA
VERTEBRATES
550601* - Medicine- Unsealed Radionuclides in Diagnostics