Carotene-bleaching activities of lipoxygenase and heme proteins as studied by a direct spectrophotometric method

Abstract

A procedure is described for the direct spectrophotometric study of carotene-bleaching in aqueous solution. Beta-carotene, with or without added linoleate, is dissolved in suitable buffers with Tween 80, the decrease in absorbance at 460 nm is recorded, and the initial rate of bleaching is computed from the bleaching curves. The technique was applied to a comparative study of the catalytic effects of lipoxygenase, cytochrome c and peroxidase. The latter enzyme, which displayed much less activity in the presence of linoleate, compared to the other two catalysts, was the only one to cause significant carotene bleaching in the absence of added fatty acids. Activity was linearly related to the concentrations of lipoxygenase and cytochrome c, but not to the amount of peroxidase. The inhibitory effects of some antioxidants on carotene bleaching in the presence of the three catalysts were studied. © 1971.