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Updated: Mar 18, 2026
![Radiosynthesis of 1-2-[18F]Fluoroethyl-L-Tryptophan using a One-pot, Two-step Protocol](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F63025.jpg&w=3840&q=50)
Radiosynthesis of 1-2-[18F]Fluoroethyl-L-Tryptophan using a One-pot, Two-step Protocol
Published on: September 21, 2021
Reaction of peroxynitrite with L-tryptophan
S Padmaja1, M S Ramazenian1, P L Bounds2
1a Department of Chemistry , Louisiana State University , Baton Rouge , Louisiana , U.S.A.
Abstract:
The reaction between peroxynitrous acid (hydrogen oxoperoxonitrate) and L-tryptophan is 130 M(-1)s(-1) at 25°C. The pH dependence of the second-order rate constant shows a maximum at pH 5.1. The enthalpy and entropy of activation at pH 7.1 are 10.6 ± 0.4 kcal.mol(-1) and -16 ± 2 cal.mol(-1)K(-1) respectively. High-performance liquid chromatography analysis revealed a number of reaction products, two of which were identified as 5- and 6- nitrotryptophan. Hydroxytryptophans were not observed, even at low peroxynitrite concentrations where most of the peroxynitrite decays to nitrate via a first-order process. These results support the hypothesis that isomerization of protonated peroxynitrite to nitrate does not involve formation of the hydroxyl radical.
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