Effect of Calcium on the Oxidation of Linoleic Acid by Potato (Solanum tuberosum Var. Desiree) Tuber 5-Lipoxygenase

When the effect of calcium on the oxidation of linoleic acid by potato tuber 5-lipoxygenase (LOX) was investigated, it was seen to promote the enzyme's activity at pH values higher than the optimum pH of 6.3, resulting in an enzyme activation at alkaline pH. Kinetic analysis of calcium activation at different pH values revealed that the cation abolished the inhibition by high substrate concentration, which occurs in the absence of Ca2+, thus leading to activation at high substrate concentration. Studies were conducted to investigate the influence of Ca2+ on the physicochemical nature of the substrate and its effect on the LOX activity expression. It was concluded that the aggregation mode rather than the aggregation state of linoleic acid is responsible for potato 5-LOX changes. Keywords: Lipoxygenase; calcium; linoleic acid; fluorescence; scattering