EFFECTIVENESS OF TALC AS ADSORBENT FOR STABILIZATION AND EXPRESSION OF PISUM-SATIVUM HORTENSE CV SOLARA LIPOXYGENASE-LYASE COUPLED ACTIVITIES

Pisum sativum hortense cv. Solara lipoxygenase differs from previously described lipoxygenases by the presence, at optimum pH, of dual activ ities that can convert linoleic acid into two products, 9-hydroperoxyo ctadecadienoic acid by a classical lipoxygenase activity and 2,4-decad ienal by lyase activity on an intermediate peroxyl radical. This enzym e is a very labile protein and can lose activity during or after the p urification procedure. In order to overcome this inconvenience, we imm obilized P. sativum lipoxygenase-lyase by adsorption on talc and we ex plored the evolution and stability of both activities after adsorption . For lipoxygenase or lyase activity, we obtained a specific immobiliz ation on talc with an increase in long-term stability at 4 degrees C i n comparison to free enzyme and especially for immobilized lyase activ ity (60% of activity after 30 days). Immobilized enzymes appeared to b e less sensitive to inhibitors than free, but the increase in IC50 val ues for immobilized enzymes was in fact the result of a nonspecific ad sorption of inhibitor. Therefore, despite the difference between IC50 values, free and immobilized enzyme behavior toward inhibitors were co mparable.