The catabolism of L-tyrosine by an Arthrobacter sp.

An Arthrobacter sp. metabolizes L-tyrosine by a pathway involving 3,4-dihydroxyphenyl-acetate as a key intermediate. p-Hydroxyphenylpyruvate is formed from tyrosine by an aminotransferase specifically requiring α-ketoglutarate for activity, and is then converted to p-hydroxyphenylacetate by an oxidative decarboxylation. p-Hydroxyphenylacetaldehyde is not an intermediate in the formation of p-hydroxyphenylacetate. Extracts of the bacterium oxidize 3,4-dihydroxyphenylacetate to δ-carboxymethyl-α-hydroxymuconic acid which, when supplemented with 2 mol of diphosphopyridine dinucleotide, results in the production of stoichiometric amounts of succinate and pyruvate.