Common techniques for measuring the capacity and activity of antioxidants are spectrophotometry, fluorescent, liquid and gas chromathography that have some limitations including in sample preparation. Electrochemical biosensor is a developed alternative method to study the antioxidant capacity because its rapidity, validity and low cost. The immobilization superoxide dismutase extract from Deinococcus radioduras on a zeolite nanocomposite modified electrode for antioxidant biosensor was studied. Cyclic voltammetry (CV) were employed to investigate the catalytic behavior of the biosensor. The current response was found to have a direct linear relationship with the concentration of xanthine. Optimum conditions for SOD activity was at pH 9, 300C temperature , 137.5 mg zeolite , and 3 U/ml SOD for pure SOD and pH 9, 300C temperature , 137.5 mg zeolite , and 1500µg/mL SOD for D. radiodurans SOD. Dismutation reaction kinetics of superoxide catalyzed by SOD followed the Lineweaver-Burk kinetics with D. radiodurans SOD KMapp value was smaller than pure SOD. In conclusion, a zeolite nanocomposite provided had a great potential for SOD extract D. radiodurans immobilization as antioxidant biosensor.
Key words: antioxidant biosensor, superoxide dismutase (SOD), Deinococcus radiodurans, zeolite nanocomposite, enzyme kinetic
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