Engineering Enzyme Cascades for Sustainable Biocatalysis: From Concept to Industrial Application

Background: Enzyme cascades represent an emerging paradigm in sustainable biocatalysis by enabling the sequential transformation of substrates into value-added products within a single reaction system. Mimicking the efficiency and selectivity of metabolic pathways, engineered enzyme cascades reduce the need for intermediate purification, minimize chemical waste, and allow for process intensification in green chemistry and industrial biotechnology. These systems hold particular promise for synthesizing complex pharmaceuticals, fine chemicals, and bio-based materials under mild, environmentally benign conditions. Methods and Results: This review explores the design, optimization, and application of multi-enzyme cascades in biocatalytic processes. Strategies include co-expression of enzymes in microbial hosts, in vitro enzyme assembly, compartmentalization in microreactors or scaffolds, and use of cofactor regeneration systems to enhance efficiency. Enzyme selection is driven by substrate compatibility, reaction thermodynamics, and operational stability. Advances in protein engineering, directed evolution, and computational pathway design have expanded the scope of feasible cascades, enabling stereoselective and regioselective transformations that are difficult to achieve via traditional chemical synthesis. Case studies highlight successful industrial applications such as chiral amine synthesis, biomass valorization, and enzymatic polymerization. Integration with flow chemistry and immobilization technologies has further improved scalability and reusability. However, challenges remain in balancing enzyme kinetics, managing metabolic cross-talk, and achieving robust performance under process conditions. Conclusion: Engineered enzyme cascades are redefining the landscape of biocatalysis by providing efficient, scalable, and eco-friendly alternatives to conventional synthetic routes. Continued innovations in enzyme design, pathway integration, and reactor engineering will accelerate the deployment of cascade biocatalysis in industrial settings, contributing to a more sustainable chemical economy.