5.1.3.3 | efficient stereospecific enzymatic synthesis of L-[15N]-valine, L-[15N]-leucine, L-[15N]-norvaline, L-[15N]-norleucine and L-[15N]-isoleucine from the corresponding alpha-keto acids by coupling the reactions catalysed by leucine dehydrogenase and glucose dehydrogenase/galactose mutarotase. Giving high yields of L-amino acids, the procedure is economical and easy to perform and to monitor at a synthetically useful scale of 1-10 g. Substrates alpha-ketoisovalerate, alpha-ketoisocaproate, alpha-ketovalerate, alpha-ketocaproateand alpha-keto-beta-methylvalerate are converted to products L-valine, L-leucine, L-norvaline, L-isoleucine with yields of 90%, 92.5%, 92%, 80%, and 95%, respectively |