Microbial preparation of L-[15N]tyrosine and [15N]tyramine and their gas chromatographic-mass spectrometric analyses

The preparation of L-15N]tyrosine and 15N]tyramine by microbial synthesis is described. Immobilized Erwinia herbicola cells were added to a reaction mixture containing phenol, pyruvic acid, and 15NH4Cl. The reaction was driven by excess nonlabeled pyruvate and phenol. Under these denaturing concentrations of phenol, immobilized cells were more effective than free ones. Gram quantities of L-15N]tyrosine were obtained without label dilution. The conversion of this L-15N]tyrosine into 15N]tyramine by Streptococcus faecalis was performed at maximal efficiency. Gas chromatographic-mass spectrometric studies and 1H and 15N NMR analyses of the labeled compounds are reported.