A novel approach for bioconjugation of Rhizomucor miehei lipase (RML) onto amine-functionalized supports; Application for enantioselective resolution of rac-ibuprofen.

Since the amine groups are highly reactive toward various functional moieties, the formation of covalent bonds between a biomolecule and an insoluble amine-functionalized support is the most frequently used technique in immobilization protocols. A new approach based on the Ugi four-component reaction was used for immobilization of Rhizomucor miehei lipase (RML) as a model enzyme on amine-functionalized silica and silica nanoparticles (SBA-15). For this, the amine-modified supports were prepared and the structural properties of the functionalized supports, prior to and after functionalization were characterized by using IR, SEM, TGA, DTA, TEM. Immobilization of RML on the aminated carriers was performed under extremely mild conditions (25 °C, pH 7). The results revealed very rapid immobilization of 150 and 200 mg of RML on 1 g of silica-NH2 and SBA-NH2, respectively, producing 95-100% of immobilization yield. The specific activity and optimum pH of the immobilized preparations and the effect of temperature and co-solvents on their stabilities as well as the reusability of the derivatives were tested. The immobilized preparations were also used as enantioselective catalyst in kinetic resolution of racemic ibuprofen. Among them, Silica-RML showed the best selectivity with 92.2% enantiomeric excess (ee) and E-value of 33.9.