Bio-electrode in Mechanistic Study of Lipoxygenase with Fatty Acids from Cooking Palm Oil

In this work a two-enzyme system catalyzing two consecutive reactions, namely, (i) Candida rugosa lipase type VII hydrolyzed the cooking palm oil producing fatty acids and (ii) soybean lipoxygenase-1 (type I-B) (SLO) in modified Nafion membrane carbon electrode oxidized the fatty acids to generate cathodic current. The hydrolysis was optimum at pH 7.5, temperature 37 °C, incubation time 60 min and the respective weights of enzyme and substrate 0.1 and 2 g. Cyclic voltammograms at the optimized conditions showed that the introduction of lipase to the substrate of oil emulsion has increased the cathodic current density. Parameters such as potassium phosphate buffer (pH 7) and SLO (0.4 mg mL-1) were also crucial for a higher current density. The dodecyl trimethyl ammonium bromide, used to modify the Nafion membrane, was found to be the most suitable salt for the immobilization of the lipoxygenase enzyme. The results indicate that this could provide the basis for the construction of a bio-cathode in the bio-fuel cell.