Protein aggregates facilitated by polar aprotic solvents as carriers for enzyme immobilization

Protein aggregates are extremely useful in fields such as bioseparation, biocatalysis, and bioadhesives. The development and use of protein aggregates, however, are in their infancy. In this study, emerging protein aggregates were developed through protein self-assembly using polar aprotic solvents coupled with halides. The polar aprotic solvent molecules, including dimethyl sulfoxide (DMSO), were inserted into the hydration shell of proteins such as ovalbumin (OVA), bovine serum albumin, and whey protein to partially exchange water molecules via van der Waals and electrostatic interactions to alter the surface polarity of the protein. Then, the halide ions were allowed to bind to proteins via electrostatic interactions and cause the self-assembly of proteins into aggregates. Under optimal conditions, the yield of OVA-DMSO protein aggregates reached 91.2 ± 1.52 %. OVA-DMSO-EDC/NHS-CA showed excellent enzymatic properties, and the production of calcium carbonate reached 7.1 ± 0.4 mg at 37 °C for 10 min. Additionally, other enzymes, such as L-TA, had high activity after being fixed with OVA-DMSO. These innovative protein aggregates are highly valuable for developing biomaterials.