Improvement of DERA activity and stability in the synthesis of statin precursors by immobilization on magnetic nanoparticles

Deoxyribose-phosphate aldolase (DERA), an enzyme applied in the synthesis of precursors for statin production, was immobilized on magnetic nanoparticles (MNPs). The silanized MNPs were functionalized/activated by several agents with different concentrations: APTMS/APTES-glutaraldehyde, APTMS/APTES-benzoquinone, APTMS/APTES-succinic anhydride and GPTMS. APTES-succinic anhydride (15%) provided the best result, and modification of the immobilization conditions was performed. The highest obtained retained activity and stability of 179% and 60%, respectively, were at pH 6.5 and 20 °C. A kinetic model for the immobilized enzyme reaction was developed and validated in a batch reactor. In reusability tests, immobilized DERA showed better stability than the free enzyme and maintained 70% enzyme activity after three cycles, while an almost complete loss of activity for the free enzyme after the second cycle was noticed. Higher stability and hyperactivation of the DERA enzyme were achieved by covalent bonding to magnetic nanoparticles with succinic anhydride as an activating agent.