Separation And Purification Of Lysozyme With ZnO-polyoxometalate Composite

Polyoxometalates(POMs)is a kind of acidic anionic oxides widely applied in the field of catalysis,medicine and materials science,due to their good oxidation-reduction ability,thermal stability and excellent optical,electrical and magnetic properties.Recently,the interactions between POMs and proteins have been gaining increasing interest,thus a new POMs-based composite is prepared and used for the selective separation and purification of lysozyme in present study.The incorporation of Keggin-structured phosphotungstate(PW11)into zinc oxide(ZnO)by electrostatic interaction gives rise to a novel composite,namely PW11@ZnO.The composition and structure of the composite are characterized by the techniques of Fourier transform infrared(FT-IR),X ray diffraction(XRD),thermogravimetry(TG),and transmission electron microscope(TEM).The characterization results show that the obtained PW11@ZnO are rod-like material with a diameter of 20-60 nm and a length of 200-800 nm.The interaction between PW11@ZnO and lysozyme offers the PW11@ZnO composite excellent adsorption performance towards lysozyme.Under pH 11.0,with 3 mg PW11@ZnO composite as adsorbent and an adsorption time of 10 min,the adsorption efficiency of 1 mL 100 ?g mL-1 lysozyme is 92.5%.The adsorption behavior of lysozyme on the surface of PW11@ZnO composite fits well with the Langmuir model.The maximum adsorption capacity is deduced to be 117.64 mg g-1.The adsorbed lysozyme can be efficiently recovered with SDS solution(0.5%,m/m),giving rising to a recovery of 88.75%.A PW11@ZnO-based solid-phase extraction procedure is thus developed for the separation and purification of lysozyme.Circular dichroism spectra results indicate that the adsorption/desorption processes nearly pose any effect on the structure of lysozyme.The PW11@ZnO-based solid-phase extraction procedure is applied to the separation and purification of lysozyme from egg white sample.SDS-PAGE results suggest that lysozyme of high purity is obtained.