Tyrosine ammonia lyase (L-tyrosine ammonia-lyase, TAL or Tyrase) is an enzyme in the natural phenols biosynthesis pathway. It transforms L-tyrosine into p-coumaric acid. Tyrosine ammonia lyase (L-tyrosine ammonia-lyase, TAL or Tyrase) is an enzyme in the natural phenols biosynthesis pathway. It transforms L-tyrosine into p-coumaric acid.