Liu Can, Xu Jiakun, Gao Shu-Qin, He Bo, Wei Chuan-Wan, Wang Xiao-Juan, Wang Zhonghua, Lin Ying-Wu
School of Chemistry and Chemical Engineering, University of South China Hengyang 421001 China
Yellow Sea Fisheries Research Institute Qingdao 266071 China.
RSC Adv. 2018 Sep 26;8(58):33325-33330. doi: 10.1039/c8ra07825d. eCollection 2018 Sep 24.
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 s) 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.
鉴于当今对蓝色染料的需求，开发一种用于生产靛蓝的绿色高效生物催化剂具有实际重要性。近年来，人工酶的设计已显示出吸引力。在先前的一项研究中，我们构建了一种具有新型酪氨酸 - 血红素交联的抹香鲸肌红蛋白单突变体F43Y Mb。在本研究中，我们发现它能够高效催化吲哚氧化为靛蓝，与文献中迄今报道的最高产率（约20%）相比，产率高达54%。通过进一步修饰血红素活性位点，我们构建了F43Y/H64D Mb双突变体，它在基于肌红蛋白设计的人工酶中表现出最高的催化效率（198 M⁻¹ s⁻¹）。此外，发现F43Y Mb和F43Y/H64D Mb两者产生靛蓝产物的化学选择性高达约80%。基于该反应体系，我们还建立了一种便捷的绿色染色方法，即在靛蓝生物合成过程中对棉织物进行染色，随后进一步喷洒浓缩靛蓝，无需强酸/强碱或任何还原剂。用蓝色对白色棉织物成功染色进一步表明所设计的酶和染色方法在未来具有实际应用价值。
