人工金属酶研究进展

Research Progress of Artificial Metalloenzymes

金属酶由金属辅因子和蛋白骨架构成。金属辅因子提供催化活性,是金属酶发挥功能的关键,而蛋白骨架为金属辅因子提供附着位点,同时提供手性环境。天然金属酶种类较多,可催化羟基化、环氧化等反应,其辅因子主要以金属离子或金属配体的形式存在,所含金属元素以Fe、Cu、Zn居多,部分天然金属酶也含Mn等金属元素。然而,由于天然金属酶难以催化非天然底物,且部分金属酶体外催化效率低、自身稳定性较差,无法得以广泛应用。近年来研究发现,通过对起催化功能的金属辅因子和提供酶促反应微环境的蛋白骨架进行理性设计构建人工金属酶(artificial metalloenzymes,ArMs),可提高金属酶的催化效率或使其能够催化多种天然和非天然反应。此外,利用纳米技术修饰人工金属酶可以提高金属酶的稳定性和可调控性,为人工金属酶的优化提供了新思路。总结近年来人工金属酶领域取得的成果,着重介绍构建人工金属酶策略方面的研究进展,包括金属辅因子的改造、蛋白骨架的设计、基于纳米技术的修饰等,并展望了设计改造人工金属酶所面临的机遇和挑战,以期为人工金属酶的设计和应用提供参考。

Enzymes with high efficiency and specificity have attracted much attention from researchers.Among them,metalloenzymes account for about 1/3 of natural enzymes.Metalloenzymes are generally composed of metal cofactors and corresponding protein scaffolds,in which the metal cofactors provide the active center.The protein scaffolds provide the chiral environment and attachment sites for metal cofactors.Existing studies have revealed that metalloenzymes fail to work without metal cofactors.The metal cofactors mainly exist in the form of metal ions or metal ligands.Among the natural metalloenzymes discovered so far,the metal elements in metal cofactors are mainly Fe,Cu,and Zn.Besides,there are also Mn and other metal elements.Metalloenzymes play an important role in organisms,including signal transduction and immune regulation.Various metalloenzymes can catalyze different reactions,such as hydroxylation and epoxidation.However,it is difficult for natural metalloenzymes to catalyze nonnatural substrates.Some metalloenzymes have low catalytic efficiency and poor stability in vitro,making them unable to be widely used.Recently,rapidly developed biotechnology has accelerated the development of metalloenzymes.By simulating natural metalloenzymes,artificial metalloenzymes(ArMs)have been constructed continuously.The appearance of ArMs has expanded reaction types.In summary,three main strategies have been applied in designing ArMs,including the reconstruction of cofactors,design of protein scaffolds,and modification of nanoparticles.The reconstruction of cofactors is mainly achieved by chemical modification and replacement.Design of protein scaffolds is achieved by selecting some stable structures and utilizing computer-aided methods.Notably,the development of nanotechnology has also provided good ideas for redesigning ArMs.The enzyme property can be improved by binding metalloenzymes to the surface of nanometers or being embedded in nanoparticles.Herein,we summarize some achievements of ArMs in recent years.A brief introduction about the challenges and opportunities faced by ArMs is provided,which is helpful for the design and application of ArMs.