Interaction between chloroplast pigments and lipoxygenase enzymatic extract of olives.

Lipoxygenase activity in olive fruits increases considerably when the enzyme is extracted using extraction buffer with ethylenediaminetetraacetate, Triton X-100, dithiothreitol, sodium meta-bisulfite, and hydrated polyvinylpolypyrrolidone. In the absence of these compounds the activity measured of the crude extract is almost negligible, and further effects of the enzymatic reaction, such as bleaching activity on chloroplast pigments, do not appear. Moreover, when the oxidizing level of the medium is increased by the addition of linoleic acid or soybean lipoxygenase with linoleic acid, the crude enzymatic extracts of olives reduce the destructive capacity of soybean lipoxygenase on chlorophylls to one-sixth. These results suggest a double pigment protection against lipoxygenase in the olive crude extract, one inhibiting the enzyme and the other interrupting the chain of oxidative reactions beginning with hydroperoxide formation.