Practical techniques for protein crystallization: additive assistance and external field intensification

Abstract

Crystallization is an important unit operation in industry, and proteins are widely studied owing to their biological activity and multiple functions. Protein crystals can not only facilitate the elucidation of protein structural information but also have important prospects in biopharmaceuticals. However, owing to their high molecular weight and complex structure, most proteins are difficult to crystallize or the crystallization processes are difficult to control effectively. This paper aims to provide an overview of recent reinforcement techniques for protein crystallization. Several important additive applications and principles in protein crystallization are comprehensively reviewed, including ionic liquids (ILs), deep eutectic solvents (DESs), and molecularly imprinted polymers (MIPs). The mechanism of external fields, including magnetic, electric, ultrasonic, shear, and light fields, enhancing protein crystallization are described and summarized. Finally, the challenges and future research prospects of protein crystallization are proposed. This work is expected to guide the rational design of the protein crystallization process.