Some enzymic syntheses of 15N-L-aspartic acid and 15N-L-glutamic acid

Abstract

Some methods for the preparation of 15N-L-aspartic acid and 15N-L-glutamic acid using enzyme catalyzed reactions are described. 15N-L-Aspartic acid is prepared by the addition of ammonia to fumaric acid, catalyzing the reaction with aspartase which was partially purified from E. coli. 15N-L-Glutamic acid with a high 15N/14N ratio is prepared by transamination with 15N-L-aspartic acid catalyzed by aspartate aminotransferase. 15N-L-Glutamic acid with a low 15N/14N ratio is prepared by a glutamic acid dehydrogenase catalyzed exchange of L-glutamic acid with 15N-ammonia. These enzymes are commercially available. Since efficient utilization of 15N is obtained, aspartic acid or glutamic acid may be prepared with any desired 15N/14N ratio.