Lipoxygenase 3-carotene

Grosch, W. and Laskawy, G., Co-oxidation of carotenes requires one soybean lipoxygenase isoenzyme, Biochim. Biophys. Acta, 575, 439, 1979. 

Yeum, K.-J. et al. (1995). Similar metabolites formed from beta-carotene by human gastric mucosal homogenates, lipoxygenase, or linoleic acid hydroperoxyde. Arch. Biochem. Biophys. 321(1) 167-174. 

Yeum, K. J., Y. C. Leekim et al. (1994). In vitro metabolism of beta-carotene by lipoxygenase and human stomach mucosal homogenates. FASEB J. 8(4) A192-A192. 

Considerable purification of lipoxygenase from soybeans was achieved by Balls et al (15), They used conventional protein purification methods and the carotene oxidase reaction to follow the enzyme activity. Theorell et al, (16), in 1947, crystallized the enzyme, or more correctly, one of the several isoenzymes in soybean. We believe this was lipoxygenase-1 as described later. 

Isoenzymes. Kies (90), who questioned the identity of lipoxygenase and carotene oxidase, thought that the lipoxygenase activity of soybeans was caused by more than one enzyme. She discovered that a partially... 

In addition lipohydroperoxides formed by C-15 lipoxygenase after its homolysis can give rise to lipid alkoxyl radicals which induce cooxidation of other unsaturated lipids such as p-carotene [8] (Figure 4). 

Figure 4, The cooxidation of P-carotene (X.=450 nm) by secondary lipid free radicals which formed during arachidonic acid peroxidation (A,=233 nm) by animal (rabbit reticulocyte) C-15 lipoxygenase in the water...

The destruction of p-carotene during lipid peroxidation is readily observed by bleaching of the carotene color (44). Presumably, p-carotene oxidation is initiated by H-abstraction, and such a mechanism has been proposed for the cooxidation of carotenoids during the lipoxygenase catalyzed oxidation of polyunsaturated fatty acids (45), as shown by Reaction Q. 

Enzymes of this type were formerly known as fat oxidase, carotene oxidase, and lipoxidase lipoxydase in French) and have also been listed under E.C. 1.99.2.1 and E.C. 1.13.1.13. It should be emphasized that several species of enzyme, distinguishable by substrate and product specificities as well as by physical properties, are covered by the generic term lipoxygenase. ... 

Lipoxygenases from different sources differ in their cooxidation activity. Enzymes from peas and beans (Phaseolus sp.) and the LOX-2 from soybean have a high cooxidation potential potato LOX is intermediate, whereas wheat, flax, and soybean LOX-1 have poor cooxidation activity (Grosch et al., 1976, 1977). Thus, the carotene oxidase activity of soybeans is associated with the LOX-2 isoenzyme, and this explains the observed selective loss of carotenoid bleaching activity during the purification and heat treatment of the classic (i.e., LOX-1) enzyme from soybean (Kies et al., 1969). 

The presence of a lipid-oxidizing enzyme in plants, then termed lipoxidase, was first described by Andre and Hou in 1932 [1]. A pigment bleaching property, attributed to a separate enzyme activity described as carotene oxidase, was later found to originate from this enzyme as well [2]. The name lipoxygenase (linoleateioxygen oxidoreductase, EC 1.13.11.12) is now used for this enzyme. 

Grosch, W., Laskawy, G. and Weber, F. Formation of volatile carbonyl compounds and cooxidation of j8-carotene by lipoxygenase from wheat, potato, flax, and beans. J. Agric. Food Chem. 24, 456-459 (1976). 

Hildebrand, D.F. and Hymowitz, T. (1982) Carotene and chlorophyll bleaching by soybeans with and without seed lipoxygenases-1. /. Agric. Food Chem. 30, 705-708. 

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