Effects of P-carotene on soybean lipoxygenase activity:kinetic studies

摘要

beta-carotene directly influences the amount of soybean lipoxygenase (LOX) in the reaction medium available for the catalytic conversion of linoleic acid into corresponding hydroperoxides. Inhibition of LOX by p-carotene was predominantly of the noncompetitive type. The mean Km(app) value was estimated to be 13.25muM .15 muM for linoleic acid while the mean K_i value was estimated to be 2.56muM+-0.14muM for -carotene. Vm(app) values decreased from 1.90AA234 nm/min to 0.38AA234 nm/min as the concentration of beta-carotene increased. The IC50 value for beta-carotene was 2.49 muM+-0.21muM. It is shown here that beta-carotene is an efficient LOX inhibitor, effective at low-level concentration enzyme-dependent peroxidation of linoleic acid. Presence of beta-carotene keeps LOX in its reduced form of Fe(II) and the oxidation of linoleic acid is prevented.