Recent advances in discovery, protein engineering, and heterologous production of ketose 3-epimerase for rare sugar biosynthesis

Background

Ketose 3-epimerase (KEase), with its unique C3 epimerization activity and high promiscuity, serves as a crucial biocatalyst for synthesizing various rare sugars. Due to the crucial roles of rare sugars as functional sweeteners or intermediates in the food and pharmaceutical industries, KEase has garnered widespread research attention over the past few decades.

Scope and approach

This review begins with a comprehensive overview of methodologies employed in the discovery of novel KEases, continues with a detailed discussion of enzymatic properties and practical applications of KEases, and then focuses on the approaches of protein engineering for optimizing the performance of KEase and strategies of heterologous expression for achieving high-efficiency production of KEase. This review aims to help readers understand the current research progress related to KEase while providing an informed perspective on its future developments.

Key findings and conclusions

KEases offer considerable potential in facilitating the accessibility of rare sugars. To fulfill specific application requirements, various enzyme mining methods have been established to obtain KEases with different enzymatic properties. Furthermore, effective strategies have been developed to enhance KEase in terms of both quality and quantity. To further broaden the industrial applicability of KEase for rare sugar biosynthesis, future endeavors should be focused on systematically optimizing each step in the process, from enzyme sourcing to enzyme production, by integrating multiple strategies.