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

Abstract

The enzymatic synthesis of l‐tryptophan and its derivative 5′‐hydroxy‐l‐tryptophan labeled with deuterium and tritium at the α‐carbon position is reported. The mixture containing S‐methyl‐l‐cysteine, indole or 5‐hydroxyindole dissolved in deuteriated or tritiated water has been converted to [2‐2H]‐l‐tryptophan, [2‐3H]‐l‐tryptophan, 5′‐hydroxy‐[2‐2H]‐l‐tryptophan, and 5′‐hydroxy‐[2‐3H]‐l‐tryptophan, respectively, in a one‐pot reaction using the enzyme tryptophanase. The same reaction carried out in heavy water with THO added yielded either doubly labeled [2‐2H/3H]‐l‐tryptophan or 5′‐hydroxy‐[2‐2H/3H]‐l‐tryptophan. Copyright © 2003 John Wiley & Sons, Ltd.

“Dial Up and Lock In”: Asymmetric Organo-Brønsted Acid Catalysis Incorporating Stable Isotopes

“…Optically active aand/or b-deuterated natural and unnatural a-amino acids are important (bio)chemical motifs (see Figures 2H-2P) mainly generated via multi-step, enolatebased chemistry using Schö llkopf bis-lactim ethers, Evans oxazolidinones, Williams' oxazoline, Oppolzers' sultam, or Seebach imidazolidinone chiral auxiliaries. [127][128][129][130][131][132][133][134][135][136][137][138][139][140][141] The development of an operationally simple, catalysis-based protocol that transforms easily accessible starting materials into cis-aziridines ''en route'' to natural or unnatural, optically active, isotope-enhanced a-amino acids holds considerable merit. Isotopeenhanced a-amino acids are valuable bioprobes that have been used for investigating protein-protein interactions, 142 identifying unknown compounds from orphan gene clusters (the so-called genomisotopic approach), 143 and determining the metabolic S63 and S64) were afforded in excellent 93% and 90% yields, respectively (Figure 7).…”

Synthesis of deuterium-labelled halogen derivatives of L-tryptophan catalysed by tryptophanase

“…All halogenated deuterium-labelled isotopomers of l- Trp (1, 2, 3 and 4) were obtained by a coupling reaction between the halogenated derivatives of indole (with fluorine, bromine or chlorine substituent) and S-methyl-l-cysteine, catalysed by TPase (EC 4.1.99.1) from E. coli in a completely deuterated medium, using modified methods as described earlier [23][24][25] (Figure 2). In accordance with the mechanism of the lyase reaction [2,[26][27][28] and its reverse, postulating the formation of an intermediate PLP-bound enamine structure of the coupling agent, and the subsequent addition of the indole (or its derivative) and a 1 H/ 2 H ion from the medium to its double bond, a 100% labelling in the α-position was attained ( Table 2).…”

Synthesis of Isotopically Labeled α‐Amino Acids

“…The use of labeled substrates for these reactions has led to the synthesis of a wide range of isotopically labeled analogs of tyrosine, phenylalanine, and tryptophan [16][17][18][19][20][21]. For example, reaction of L-serine 7 with ½2; 6-13 C 2 phenol 6 in the presence of a b-tyrosinase enzyme from Erwinia herbicola gave [3 0 ,5 0 -13 C 2 ]L-tyrosine 8 in 91% yield (Scheme 11.5) [20].…”