Green and efficient biosynthesis of indigo from indole by engineered myoglobins

• Published in: RSC Advances
• Main Authors: Liu, Can, Xu, Jiakun, Gao, Shu-Qin, He, Bo, Wei, Chuan-Wan, Wang, Xiao-Juan, Wang, Zhonghua, Lin, Ying-Wu
• Format: Text
• Language: English
• Published: The Royal Society of Chemistry 2018
• Subjects: Chemistry; Sperm whale
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9086478/; https://doi.org/10.1039/c8ra07825d

With the demand nowadays for blue dyes, it is of practical importance to develop a green and efficient biocatalyst for the production of indigo. The design of artificial enzymes has been shown to be attractive in recent years. In a previous study, we engineered a single mutant of sperm whale myoglobin, F43Y Mb, with a novel Tyr-heme cross-link. In this study, we found that it can efficiently catalyze the oxidation of indole to indigo, with a yield as high as 54% compared to the highest yield (∼20%) reported to date in the literature. By further modifying the heme active site, we engineered a double mutant of F43Y/H64D Mb, which exhibited the highest catalytic efficiency (198 M(−1) s(−1)) among the artificial enzymes designed in Mb. Moreover, both F43Y Mb and F43Y/H64D Mb were found to produce the indigo product with a chemoselectivity as high as ∼80%. Based on the reaction system, we also established a convenient and green dyeing method by dyeing a cotton textile during the biosynthesis of indigo, followed by further spraying the concentrated indigo, without the need of strong acids/bases or any reducing agents. The successful application of dyeing a white cotton textile with a blue color further indicates that the designed enzyme and the dyeing method have practical applications in the future.