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Directed Evolution of a Tryptophan 2,3‐Dioxygenase for the Diastereoselective Monooxygenation of Tryptophans
Author(s) -
Wei Yanxin,
Lu Chen,
Jiang Shengsheng,
Zhang Yanyan,
Li Qiuchun,
Bai WenJu,
Wang Xiqing
Publication year - 2020
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201911825
Subject(s) - tryptophan , chemistry , indole test , dioxygenase , stereochemistry , medicinal chemistry , enzyme , organic chemistry , amino acid , biochemistry
Herein, we report an engineered enzyme that can monooxygenate unprotected tryptophan into the corresponding 3a‐hydroxyhexahydropyrrolo[2,3‐b]indole‐2‐carboxylic acid (HPIC) in a single, scalable step with excellent turnover number and diastereoselectivity. Taking advantage of directed evolution, we analyzed the stepwise oxygen‐insertion mechanism of tryptophan 2,3‐dioxygenases, and transformed tryptophan 2,3‐dioxygenase from Xanthomonas campestris into a monooxygenase for oxidative cyclization of tryptophans. It was revealed that residue F51 is vital in determining the product ratio of HPIC to N ′‐formylkynurenine. Our reactions and purification procedures use no organic solvents, resulting in an eco‐friendly method to prepare HPICs for further applications.