ABSTRACT
Lipoxygenase was discovered in 1928 when R. M. Bohn and G. H. de Haas reported the presence of a carotene-destroying enzyme, “carotene oxidase,” in soybeans. Lipoxygenase is found in a wide variety of plants, particularly the legumes. Addition of organic solvents or detergents to solubilize the substrate at low pH values often results in peculiar pH-activity profiles because of their effects on the triglyceride micelles, the substrate for lipoxygenases. With linoleic acid and O2 as the substrates, detailed kinetic studies indicate that both soybean lipoxygenase-1 and English pea lipoxygenase-1 follow a Bi Bi Ordered Sequential mechanism, not a Ping-Pong mechanism. Peroxidation by lipoxygenase is inhibited by compounds such as nordihydroguaiacetic acid, propyl gallate, and a-tocopherol, which are lipid antioxidants. As a consequence of the action of lipoxygenase on linoleic acid there are three readily measurable changes that occur: uptake of O2, a conjugation of double bonds, and formation of a hydroperoxide.
