Self-Assembly of Magnetic Lysozyme Crystals with a Medium of Polymers

Bulk protein crystallization used in biopharming as an alternative method of protein-based biotherapeutics purification has been researched with a noticeable focus because of its advantages of low cost and high purification efficiency. We proposed a method to prepare magnetic protein crystals with targeting function using nanomagnetic spheres as the core and polymers as the medium. Lysozyme was used as a model protein, and polymers with different structural characteristics were selected to assist the molecular self-assembly of magnetic lysozyme crystals. Polymer C with free carboxyl groups provoked the largest increase in the effective supersaturation (S = 9.57), which enhanced the shortest induction time (T = 5.5 h). UV spectrum, fluorescence, molecular docking, and molecular dynamics (MD) methods were conducted to investigate the interaction law in the interface between polymers and lysozyme. Polymer C had the strongest interaction with lysozyme and promoted the most suitable change in the conformation of lysozyme, which all resulted in optimum crystallization propensities. This article provides insight into the mechanism of the interface-assisted self-assembly of magnetic lysozyme crystals, which can provide a method for selecting polymers to assist the self-assembly of functional crystals.