Enzymatic synthesis of [1-13C]- and [1-14C]-L-phenylalanine

The two isotopomers of L-phenylalanine labelled with C-13 or C-14 in the carboxylic group have been obtained by the combined chemical and enzymatic methods. [1-C-13]- or [1-C-14]-L-phenylalanine have been synthesised by conversion of [1-C-13]- or [1-C-14]CH3COONa into proper cinnamic acid species followed by ammonia addition in the presence of phenylalanine ammonia lyase, The reaction yield has been determined enzymatically and spectroscopically; radiochemical yield of C-14-compound has been determined by liquid scintillation counting, and the C-13 enrichment level has been established by C-13 NMR and mass spectroscopy methods.