| Abstract: | Lipoxygenase (LOX) is an enzyme that regioselectively introduces a hydroperoxide into polyunsaturated fatty acids (PUFA). We recently reported a procedure that immobilizes soybean LOX within an alginate sol‐gel matrix. In this study, the kinetic profile of free LOX was compared with that of the sol‐gel immobilized LOX. The temperature dependent activity profile of free LOX was optimal at 25C whereas immobilized LOX had optimal activity over the temperature range of 25–35C. Enzyme activity, measured in aqueous buffer, for both the free and immobilized LOX preparations had Km values of 2.5 and 1.40 mmoles/L, respectively, and Vmax values of 0.056 and 0.02 μmol/min, respectively. The relative rates of oxidation of linoleic acid and acylgfycerols containing linoleoyl residues catalyzed by free and immobilized LOX also were determined The results showed that both free and immobilized LOX favor linoleic acid as a substrate. Relative substrate preference for free LOX was linoleic acid >1‐monolinolein > 1,3‐dilinolein >trilinolein, and for immobilized LOX was linoleic acid >l, 3‐dilinolein >1‐monolinolein >trilinolein. In general, LOX immobilized in alginate silica sol‐gel matrix retained the physical and chemical characteristics of free LOX. |
