Synthesis of [14C]‐l‐tryptophan and [14C]‐5′‐hydroxy‐l‐tryptophan labeled in the carboxyl group

The synthesis of selectively ¹⁴C‐labeled l ‐tryptophan and its derivative 5‐hydroxy‐l ‐tryptophan using chemical and multienzymatic methods is reported. The mixture containing 1‐¹⁴C‐dl ‐alanine, indole or 5‐hydroxyindole has been converted to 1‐¹⁴C]‐l ‐tryptophan or 5′‐hydroxy‐1‐¹⁴C]‐l ‐tryptophan, respectively, in a one‐pot multienzymatic reaction using four enzymes: d ‐amino acid oxidase, catalase, glutamic‐pyruvic transaminase and tryptophanase. Copyright © 2003 John Wiley & Sons, Ltd.