The metabolism of aromatic compounds in higher plants. VII. The origin of the nitrile nitrogen atom of dhurrin (beta-D-glucopyranosyloxy-L-p-hydroxymandelonitrile).

The data obtained in these experiments show that the nitrile nitrogen of dhurrin is directly derived from the a-amino group of L-tyrosine. This is analogous to the retention of the a-amino nitrogen of valine on its conversion to linamarin (6). The biosynthetic route from L-tyrosine to dhurrin must involve the modification of the amino acid in a manner such that the C&z-N unit remains intact. 15N analyses of the amino acids isolated after L-tyrosiner4C, r5N feeding suggest that the L-tyrosine-L-alanine transaminationcouple is more active than the L-tyrosine-L-glutamic acid couple.