Circular dichroism analysis of penicillin G acylase covalently immobilized on silica nanoparticles

Bio-functionalization of silica nanoparticles was performed by covalent binding of penicillin G acylase. Structure-function analysis of free and bound enzyme using CD and activity tests revealed only minimal changes in secondary structure but an up to 80% decrease in specific activity upon immobilization. This may be caused rather by diffusion limitation than by a conformational change of the enzyme.