Synthesis ofl-Tyrosine or 3,4-Dihydroxyphenyl-l-alanine from Pyruvic Acid, Ammonia and Phenol or Pyrocatechol

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Abstract
The synthesis of l-tyrosine or 3,4-dihydroxyphenyl-l-alanine (l-dopa) from pyruvate, ammonia and phenol or pyrocatechol was studied with intact cells of Erwinia herbicola ATCC 21434 containing high tyrosine phenol lyase activity. By elemental analyses and determination of optical activity, the tyrosine or dopa synthesized was confirmed to be entirely of l-form. Maximum amount of l-tyrosine (60.5 g/liter) or l-dopa (58.5 g/liter) was formed using this enzymatic method by feeding sodium pyruvate and phenol or pyrocatechol. However, large amounts of by-products were formed in the l-dopa synthetic reaction mixture. By-products were proved to be formed from l-dopa and pyruvate by a nonenzymic reaction. pH and the temperature of reaction had intensive effects on the formation of by-products. A simple method using a boric acid-pyrocatechol complex was devised, as the feeding procedure of substrates was complicated.

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