Methods for the enzymatic synthesis of tyrosine and phenylalanine labeled with nitrogen-13

Alan S. Gelbard, Arthur J.L. Cooper, Yasuhisa Asano, Edward Nieves, Sabina Filc-Dericco, Karen C. Rosenspire

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l-[13N]Tyrosine and l-[13N]phenylalanine were synthesized using immobilized enzymes by two methods. In method 1, [13N]ammonia is converted to l-[13N]glutamate; transamination with p-hydroxyphenylpyruvate yields l-[13N]tyrosine. [13N]Tyrosine is separated from other labeled intermediates on a Poropak Q column. In method 2, phenylalanine dehydrogenase catalyzes the reversible reductive [13N]amination of either phenylpyruvate or p-hydroxyphenylpyruvate to form l-[13N]phenylalanine or l-[13N]tyrosine, respectively. The feasibility of labeling DOPA and tryptophan with 13N was also demonstrated.

Original languageEnglish (US)
Pages (from-to)229-233
Number of pages5
JournalInternational Journal of Radiation Applications and Instrumentation. Part
Issue number2
Publication statusPublished - 1990
Externally publishedYes


ASJC Scopus subject areas

  • Radiation
  • Engineering(all)

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