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Free keywords:
L-tyrosine; O-18-pattern; plant originating products; animal
originating products; food adulteration proof
Oxygen
Abstract:
dThe biosynthesis of L-tyrosine in plants by the shikimate pathway via arogenate implies that the oxygen atom in the p- position originates from D-erythrose with a delta(18)O-value near +30parts per thousand above leaf water, while its synthesis in animals by hydroxylation of external L- phenylalanine with O-2 as oxygen source and a kinetic isotope effect k(16)/k(18)congruent to1.018 demands a delta(18)O-value near +6parts per thousand. These expectations are fully confirmed by experimental data from the 180-pattern analysis of natural aromatic compounds. The result is considered as a basis for the assignment of L-tyrosine and L-tyrosine-derived material of plant or animal origin, respectively, and for the determination of the relative amounts of plant and animal material in food and animal feed.
