Purification of virus like particles from yeast cells using aqueous two-phase systems

Aqueous two-phase systems have been used for the separation and purification of recombinant virus-like particles (VLPs) from a yeast cell homogenate. Systems have been evaluated on the basis of their ability to separate VLPs from cell debris and from contaminating proteins. Two strategies are proposed for VLP separation, both involve the use of two PEG/salt aqueous two-phase systems. For separation of VLPs from cell debris systems composed of PEG 400 or 600 and (NH4)2SO4 or PEG 4000/MgSO4 can be used and for separation of VLPs from proteins PEG 4000/(NH4)2SO4 or MgSO4 and Na2SO4 are effective. The molecular weight of the PEG used and the use of additional salts (e.g. NaCl) greatly influence the effectiveness of the systems.