A haloalkane dehalogenase DhaA nanoparticle based on pullulan conjugation and polyethyleneimine adsorption

Abstract Purpose Haloalkane dehalogenase DhaA is an enzyme that can degrade the halogenated compounds. However, it could not tolerate harsh environmental conditions, which limits its practical applications. Thus, an effective strategy was necessitated to improve the stability of DhaA. Methods Pullulan is a hydrophilic polysaccharide and polyethyleneimine (PEI) is a polymer with high density of amino groups. DhaA was conjugated with acetylated pullulan and adsorbed with PEI by electrostatic interactions to form nanoparticles (PEI-pullulan-DhaA). Results As compared with DhaA, PEI-pullulan-DhaA essentially maintained the enzymatic activity of DhaA. The conjugated pullulan formed a large hydrated layer around DhaA. PEI, a cationic polymer, generated an amphiphilic environment around DhaA. PEI-pullulan-DhaA has a significantly strong stability against high temperature and low pH. PEI-pullulan-DhaA could also tolerate the hypersaline, organic solvent, and long-term storage. Conclusion PEI-pullulan-DhaA has a strong environmental stability and is promising for industrial and environmental applications.