Polyethylene glycol: Catalytic effect on the crystallization of phosphoglucomutase at high salt concentration

A cold, aqueous solution containing (NH4)2SO4 at 53% of saturation and 5.9% w/v polyethylene glycol-400 (PEG) produces PEG-rich coacervate droplets (16%(NH4)2SO4 and 37% PEG) when warmed to 25°C. In partition experiments conducted at low protein concentration, phosphoglucomutase and several other common proteins concentrate at least 20-fold in the PEG-rich phase. A temperature-induced phase separation similar to that above, but conducted in the...