Synthesis of L-[3,3,4,4,S-methyl-2H7]methionine for use as a substrate for the methionine loading test

Article abstract of DOI:10.1002/jlcr.428

Optically pure L-[3,3,4,4,S-methyl-²H₇]methionine (L-[²H₇]methionine) for use as a substrate for the methionine loading test has been prepared. The racemic [²H₇]methionine was prepared from DL-[3,3,4,4-²H₄]methionine (DL-[²H₄]methionine) by conversion of the S-CH₃ group to a C²H₃ group. The racemate was resolved by stereospecific hydrolysis of the N-acetylated derivative with acylase. After an intravenous administration of L-[²H₇]methionine in a rat, the concentration of L-[²H₇]methionine and the metabolites in plasma were determined by GC-MS-SIM. L-[²H₄]Homocysteine and L-[²H₄]methionine were detected in plasma at 30 min after dosing. These results show that L-[²H₇]methionine was converted by de-methylation and subsequent remethylation to form L-[²H₄] methionine.