Immobilization and characterization of enzyme on magnetic nanoparticles through different intermediate arms

In recent years, much attention has been paid toward synthesis of magnetic nano sized particles and their use for immobilization of enzyme. In this study, magnetic nano sized Fe3O4 particles were synthesized and covalent immobilization and characterization of lipase enzyme on magnetic nanoparticles by various intermediate arms (GA and ECH) are researched. Characterization of Fe3O4 nanoparticles was conducted using FTIR, SEM and XRD. The size of prepared nano particles was found approximately 158,2 nm diameter. Activitiy measurements of free and immobilized lipases were conducted in order to determine optimum temperature, optimum pH, storage stabilitiy, heat stability and reusability as well as kinetic parameters ( Km, Vmax, Kcat, Kcat/Km ). Optimum pH was determined as 7,0 for free and immobilized lipases. Optimum temperature was determined 40 0C for free and immobilized lipases. The termal stabilities of free and immobilized lipases have been improved greatly .For free lipase at optimum conditions Km, Vmax, Kcat, Kcat/Km values were calculated as sırasıyla 0,48 mM, 420,7 U/mg protein, 2,82x104 dk-1, 58,8x103 dk-1 mM-1 , the same values of immobilized lipase (GA) were calculated as respectively 1,3 mM, 33,6 U/mg protein, 2,25x103 dk-1, 1,73x103 dk-1 mM-1and for immobilized lipase (ECH) calculated as sırasıyla 9,4 mM, 51,7 U/mg protein, 3,47x103 dk-1, 0,37x103 dk-1 m M-1 .Reusability of immobilize lipases was investigated in a batch type reactor. After 20 reuses, residual activites of immobilized lipase were about %71 (GA) and %63 (ECH) of its initial activity. The residual activity for free lipase stored at 50C and 250C for 30 days were %37 and %23 of its initial activity, respectively. However, the immobilized lipases protected %50 (GA), %44 (ECH) and to %44 (GA) ,%28 (ECH) of its original activities at 50C and 250C,respectively for 30 days.