title: An enzymatic synthesis of 4-methyl-L-glutamic acid diastereoisomers.
abstract: (2S,4R)-"erythro"- and (2S,4S)-"threo"-4-methylglutamic acids have been prepared by glutamate dehydrogenase-catalyzed reductive amination of 2-keto-(R,S)-4-methylglutaric acid, in the presence of NH4+ ions, NAD+, and a NADH recycling system (ethanol-alcohol dehydrogenase), followed by separation by anion-exchange chromatography. Nuclear magnetic resonance, electrophoretic, chromatographic, and optical properties of both isomers are reported, together with the conditions leading to the four-carbon epimerization.
mesh_terms: D000818:Animals; D002417:Cattle; D002852:Chromatography, Ion Exchange; D005969:Glutamate Dehydrogenase; D005971:Glutamates / Q000138:chemical synthesis*; D007202:Indicators and Reagents; D008099:Liver / Q000201:enzymology; D009682:Magnetic Resonance Spectroscopy; D009904:Optical Rotation; D013237:Stereoisomerism
chemical_list: D005971:Glutamates; D007202:Indicators and Reagents; C046105:4-methylglutamic acid; D005969:Glutamate Dehydrogenase