Structural Characterization of Multienzyme Assemblies: An Overview.

Multienzyme assemblies have attracted significant attention in recent years for use in industrial applications instead of single enzymes. Owing to their ability to catalyze cascade reactions, multienzyme assemblies have become inspirational tools for the in vitro construction of multienzyme molecular machines. The use of such molecular machines could offer several advantages such as fewer side reactions, a high product yield, a fast reaction speed, easy product separation, a tolerable toxic environment, and robust system operability compared to current microbial cell catalytic systems. Besides, they can provide all the benefits found in the use of enzymes, including reusability, catalytic efficiency, and specificity. Similar to single enzymes, multienzyme assemblies could offer economical and environmentally friendly alternatives to conventional catalysts and play a central role as biocatalysts in green chemistry applications. However, detailed characterization of multienzyme assemblies and a full understanding of their mechanistic details are required for their efficient use in industrial biotransformations. Since the determination of the first enzyme structure in 1965, structural information has played a pivotal role in the characterization of enzymes and elucidation of their structure-function relationship. Among the structural biology techniques, X-ray crystallography has provided key mechanistic details into multienzyme assemblies. Here, the structural characterization of multienzyme assemblies is reviewed and several examples are provided.