15N conservation in the metabolic conversion of isoleucine to alloisoleucine in the rat.
15N,13C6-L-Isoleucine was given by stomach tube to a pair of rats and the urine excreted over the following 6 h period was collected. The urinary amino acid fraction showed that the majority of the L-alloisoleucine produced from the labeled isoleucine was formed with the 15N label intact. This fails to support the commonly held supposition that L-isoleucine and L-alloisoleucine interconversion occurs through the reversible enolization of the 2-keto-3-methylvaleric acids formed by their transamination. In contrast to 15N label conservation in L-alloisoleucine, the majority of the 15N in the administered L-isoleucine underwent exchange with 14N.
Mamer
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OA
Biomedical Mass Spectrometry Unit, McGill University, Montreal, Quebec, Canada.
Lépine
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FL
D000081:Acetamides; D000818:Animals; D001711:Biotransformation; D005463:Fluoroacetates; D008401:Gas Chromatography-Mass Spectrometry; D007202:Indicators and Reagents; D007532:Isoleucine / Q000493:pharmacokinetics* / Q000652:urine; D008297:Male; D009584:Nitrogen / Q000378:metabolism*; D009587:Nitrogen Isotopes; D017646:Organosilicon Compounds; D051381:Rats; D017207:Rats, Sprague-Dawley
D000081:Acetamides; D005463:Fluoroacetates; D007202:Indicators and Reagents; D009587:Nitrogen Isotopes; D017646:Organosilicon Compounds; D007532:Isoleucine; C059151:N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide; D009584:Nitrogen