关键词: 生物催化, 多酶催化体系, 逆合成分析, 无细胞, 底物通道, 固定化

Abstract:

The multi-enzyme catalysis system has become a hotspot in the field of bio-catalysis in recent years. Due to the catalytic process's controllability and the ease of downstream separation, more and more intracellular metabolic pathways are being developed and applied to produce fine chemicals in vitro. With the gradual maturity of multi-enzyme catalytic system construction technology, it will bring a broad application prospect for the manufacture of chemical products and pharmaceutical products in the future. In this regard, we review recently published examples of multi-enzyme catalysis, compare relevant design principles. Thermodynamics and kinetics of the reaction process and synthesis path analysis are used to design a bio-catalysis path. The critical enzymes are then mined in the pathway. By combining various assembly strategies, enzymes with different functions are cascaded into a whole structure and function unit to form a "substrate channel." Then intermediate loss and side reaction was reduced during the efficient bioconversion process from simple substrates to complex products. This method has the advantages of improving reaction efficiency, high regional selectivity and stereoselectivity, and also reducing environmental impact. Thus, biocatalysts are now widely used to produce valuable commercial chemicals, pharmaceuticals, and fuels. The target products could be obtained by the bio-catalysis process in vivo or in vitro. High-value products that are difficult to synthesize, or in an extremely complex synthesis pathway, or a very costly synthesis process by non-biological methods can now be produced in microbial hosts. To match the corresponding products, various genes in the host cell need to be optimized and fine-tuned. However, in vitro bio-catalysis can avoid these limitations. By adding a variety of enzymes to the reaction system, the product can be obtained after completing the catalysis at one time. Thus, industrial bio-fabrication has emerged as an attractive and economically viable alternative to conventional large-scale chemical synthesis. The multi-enzyme catalysis system in the synthesis of pharmaceutical chemicals (such as antibiotics, drugs for anti-cancer, cardiovascular disease treatment, liver disease treatment and psychiatric treatment) and various active ingredients (such as D-gluconic acid, terpenoids, 5-aminolevulinic acid) were discussed. The problems existing in the multi-enzyme catalytic system and the possible solutions are also summarized.

Key words: biocatalysis, multi-enzyme system, retrosynthetic analysis, cell-free, substrate channel, immobilization