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

Abstract

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.

Enzymatic synthesis of l‐tryptophan and 5prime‐hydroxy‐l‐tryptophan labeled with deuterium and tritium at the alpha‐carbon position

“…[23][24][25] The enzyme TPase decomposes l-Trp and its derivatives to pyruvic acid (Scheme 1). In turn this acid is converted into lactic acid in the presence of the enzyme lactic acid dehydrogenase, LDH, and nicotinamide dinucleotide, NADH.…”

The chemo- enzymatic synthesis of labeled l-amino acids and some of their derivatives

“…[1- 14 C]- l -Trp ( 29j ), and 5′-OH-[1- 14 C]- l -Trp ( 32d ) specifically labeled with 14 C in the carboxyl group, have been prepared using a combination of chemical and multienzymatic methods [107]. For this synthesis we applied, as an intermediate, a racemic mixture of [1- 14 C]- dl -alanine ( 33 ), which was obtained in a multistep synthesis that has been previously reported [108, 109].…”

“…Enzyme D-AAO rapidly transforms d -alanine to pyruvic acid only, therefore, to avoid the loss of half of radioactivity from the l -enantiomer we also used the second enzyme, GPT, converting l -alanine into pyruvic acid only. The medium also contained the enzyme catalase (EC 1.11.1.6) (removing the H 2 O 2 formed) and coenzymes for D-AAO and GPT, i.e., flavin adenine dinucleotide, FAD, and pyridoxal 5′-phosphate, PLP, respectively [107].

Fig.

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