Lipoxygenase anaerobic reaction

Garssen, G.J., Vliegenthart, J.F.G. and Boldingh, J. (1972). The origin and structures of dimeric fetty acids from the anaerobic reaction between soya-bean lipoxygenase, linoleic acid and its hydroperoxide. Biochem. J. 130, 435-442. 

Garssen et al. 134) observed that soybean lipoxygenase, presumably lipoxygenase-1, acting at pH 9.0 under anaerobic conditions and in the presence of linoleic acid and 13-hydroperoxy octadeca-ci5-9-trans-ll-dienoic acid i.e., the major product formed in the hydroperoxidation of linoleic acid by this enzyme) gives 13-keto-octadeca-9,ll-dienoic acid and the split products, pentane and 13-keto-trideca.-cis trans)-9-trans-ll-dienoic acid. The D-9-hydroperoxy compound cannot substitute for the L-13-hydroperoxide 135). Dimers are also formed under these conditions. These reactions do not occur under aerobic conditions. Two possible pathways for the anaerobic reaction suggested by these workers are shown in Figures 1 and 2. 

Verhagen, j., G. A. Veldink, M. R. Egmond, J. F. G. Vliegenthart, J. Boldingh, and J. Van Der Star Steady-State Kinetics of Anaerobic Reaction of Soybean Lipoxygenase-I with Linoleic Acid and I3-L-HydroperoxylinoIeic Add. Biochem. Biophys. Acta 529, 369 (1978). 

In the anaerobic reaction between linoleic acid and its 13-hydroperoxide in the presence of lipoxygenase, Cj and Qg degradation products accompany the oxo-octadecadienoate ... 

The reaction can proceed aerobically or anaerobically, proceed anaerobically only, or not occur. Despite a long-held belief to the contrary, lipoxygenase contains a prosthetic group. Highly purified isoenzymes contain one atom of Fe per molecule. The metal can be removed directly by a Fe -specific chelator or by a F -specific chelator after reduction. The occurrence, role in food, and mechanism of action of lipoxygenase are discussed. 

Lipohydroperoxide Destruction and Secondary Products. Investigators have noted that during a lipoxygenase reaction the hydroperoxide concentration, as measured with Fe(CNS)2, rises and then declines [e.g., Balls et al (15), Blain and Barr 137), Gini and Koch (138)]. This phenomenon has been attributed to a lipohydroperoxide-destroying enzyme, or lipohydroperoxidase, as well as to hematin compounds (3, 143), However Pistorius and Axelrod reproduced this phenomenon with crystalline lipoxygenase-1 (139). There is little doubt that the anaerobic destruction of lipohydroperoxide, as detailed by Garssen et al 134), is responsible for this. 

Scheme 2 Catalytic cycles of the anaerobic and aerobic lipoxygenase reactions...

In our study, the reusability of LOX immobilized in calcium-alginate beads was determined by repeatedly using the same beads for five successive reactions with linoleic acid (LA) (Fig. 2). The LOX activity was measured after each cycle, and the beads were recovered and washed with sodium borate buffer before reuse. To initiate the next cycle of oxidation, LA was added to the incubation mixture containing the recovered beads. The data (Fig. 2) demonstrates that LOX immobilized in beads can be reused at least five times without substantial loss in enzyme activity. In contrast, free lipoxygenase is typically inactivated by hydroperoxide accumulation and the partial anaerobic condition that develops in the reaction mixture (8). 

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