Self‐Inactivation by 13‐Hydroperoxylinoleic Acid and Lipohydroperoxidase Activity of the Reticulocyte Lipoxygenase

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Abstract
1 The self-inactivation of lipoxygenase from rabbit reticulocytes with linoleic acid at 37°C is caused by the product 13-hydroperoxylinoleic acid. This inactivation is promoted by either oxygen or linoleic acid. 2 Lipohydroperoxidase activity was demonstrated with 13-hydroperoxylinoleic acid plus linoleic acid as hydrogen donor under anaerobic conditions at 2°C. The products were 13-hydroxylinoleic acid, oxodienes and compounds of non-diene structure similar to those produced by soybean lipoxygenase-1. 3 13-Hydroperoxylinoleic acid also changed the absorbance and fluorescence properties of reticulocyte lipoxygenase. The results indicate that one equivalent of 13-hydroperoxylinoleic acid converts the enzyme from the ferrous state into the ferric state as described for soybean lipoxygenase-1. The spectral changes were reversed by sodium borohydride at 2°C, but not at 37°C; it is assumed that the ferric form of reticulocyte lipoxygenase suffers inactivation.