Investigation of enhancement in thermal stability of trypsin in modified Mg/Al layered double hydroxides

Mg/Al Layered Double Hydroxides (LDHs) were functionalized to immobilize the serine protease, trypsin. Three methods were implemented for immobilization: physical adsorption, entrapment and covalent cross-linking. Trypsin was immobilized in Mg/Al- NO₃^- LDH via simple adsorption. The same LDH host was modified with Sodium Dodecyl Sulphate (SDS) which assembles inside the double layer, for the enzyme to be entrapped. For covalent cross linking, LDH host was modified with vertical pillars of glutamate ions which were cross-linked to horizontally aligned dicarbonyl linkers. This cross linkage firmly holds the enzyme via Schiff’s base linkages using the free amino groups of the enzyme. Thermal stability and storage stability of the immobilized enzyme was studied in comparison with the free enzyme using trypsin activity assay experiments. The enzyme showed remarkable stability against autolysis even at higher temperatures showing the potential of modified LDHs to store trypsin at room temperature.