CHARACTERIZATION OF SOYBEAN LIPOXYGENASE IMMOBILIZED IN CROSS-LINKED PHYLLOSILICATES

Lipoxygenase (LOX) is an enzyme that regioselectively introduces the h ydroperoxide functionality into polyunsaturated fatty acids, such as l inoleic acid (LA), Hydroperoxide derivatives of polyunsaturated fatty acids are of interest because they can serve as important intermediate s in the synthesis of chemical and pharmaceutical compounds. In this s tudy, LOX was immobilized in dispersed phyllosilicate layers that were cross-linked with silicate polymers formed by the hydrolysis of tetra methyl orthosilicates. The effects of substrate concentration, reactio n temperature and solvent participation were studied on the oxidation of LA by LOX, The temperature optimum for the oxidation of LA by immob ilized LOX was 25 degrees C and values of K-m and V-max for this react ion were 1.7 mM and 0.023 mu mol/min respectively. Enzymic activity wa s stimulated by the addition of 10% (v/v) iso-octane to the reaction m ixture. The immobilized LOX preparation showed a degree of substrate p reference that demonstrated that 1,3-dilinolein was a better substrate than LA in the oxidation reaction, followed in order by 1-monolinolei n, methyl oleate and trilinolein, In general, LOX immobilized in cross linked phyllosilicates retained the physical and chemical characterist ics of free LOX.