General approach for lipases immobilization in polyelectrolyte complexes

Different lipase preparations were immobilized at various conditions in polyelectrolyte complexes (PEC) of Na-poly(styrene sulfonates) (as polyanions) and poly(diallyldimethylammonium chloride) (as polycation) with high retention of the enzyme activity. The relative activity of the immobilized enzymes strongly depends on the pH value during complex formation, the use of a buffer for the enzyme and polyelectrolyte solutions and the relative concentrations of the polyelectrolytes to lipase. The highest effective enzyme activity of about 62–68% in PEC (as difference between activity in PEC solution and in supernatant) was found for pH 9.0 and a high excess (100-fold) of the polyelectrolyte to lipase during complex formation. The use of a phosphate buffer as solvent for lipase and the polyelectrolytes resulted in activities much higher than obtained for the free lipases. Most likely, these effects are due to both (hydrophobic and electrostatic) interactions between the lipases and the polyelectrolytes.