IMMOBILIZATION OF LIPOXYGENASE IN AN ALGINATE-SILICATE SOLGEL MATRIX - FORMATION OF FATTY-ACID HYDROPEROXIDES

A method for the immobilization of lipoxygenase (LOX) in an alginate-s ilicate gel matrix was developed. In this method, a mixture of calcium alginate beads and LOX in berate buffer are dispersed into a hexane s olution of tetramethoxy-ortho-silicate (TMOS). Hydrolysis of the TMOS gives products that permeate and co-polymerize with the alginate gel t o form a colloid within the beads that entraps the LOX. Optimum reacti on conditions for sol-gel entrapment of LOX are at pH 9.0 in 0.2M bera te buffer. The composite gel, after isolation and vacuum drying, had e xcellent protein retention that has good enzyme activity and stability at room temperature. The activity of the entrapped LOX was less than the activity of the free enzyme. However, the activity of the immobili zed LOX can be restored by the addition of berate buffer and glycerol, or berate buffer saturated with an organic solvent. In contrast to th e free enzyme in solution, which loses its activity in less than one d ay, sol-gel entrapped LOX retains its activity at ambient temperature for at least 25 days and can be recycled. This report demonstrates tha t the sol-gel entrapment method for immobilizing LOX can be useful in developing a process for the oxidation of polyunsaturated fatty acids.