Ebrahim Fooladia - Department of Chemistry, Faculty of Science, University of Birjand, Birjand, South Khorasan, Iran
Susan sadeghia - Department of Clinical Biochemistry, Birjand University of Medical Sciences, Birjand, South Khorasan, Iran
Mohammad malekaneh - Department of Clinical Biochemistry, Birjand University of Medical Sciences, Birjand, South Khorasan, Iran

Molybdenum-containing enzymes, aldehyde oxidase and xanthine oxidase, are important in the oxidation of N-heterocyclic xenobiotics. These are present in the liver, as well as some othertissues of humans and other mammalian species such as the rat, guinea pig, monkey, and rabbit. In this work a bienzymatic biosensor based on the coimmobilization crude rat liver xanthine oxidase and aldehyde oxidase have been designed for inhibition study of a few purien,pyrimidine and flavoneied compounds. For this purpose, Firstly, carbon past electrode modified with Fe3O4/Go/CHIT by electrodeposition. At the next stage, the biosensor of two enzyme was prepared by dropping 20μL of crude extracted enzyme–BSA on the CPE/ Fe3O4/Go/CHIT. Thesurface of modified electrodes characterized by FE-SEM (Fig1). Results indicated the homogeneous immobilization of the crude enzymes on the modified electrode. Optimum condition for biosensor of two enzyme are BSA=1mgmL-1 pH=7.5, T=35ºC and E=-0.5V(vs.Ag/AgCl). The linear response of biosensor, limit of detection, sensitivity, for xanthine and phenanthridine are 0.1 to 18 μM and 0.1-12 μM, 0.1 μM, .05 μM ,0 .446 μA μM-1 0.65 μA μM-1and Lineweaver–Burk plot gave the apparent Km value of 2.2 μM and 4.6 μM forimmobilized enzymes respectively. All of the inhibitors tested for two enzymes, results indicated that purines compound for xanthine oxidase and pyrimidines compounds for aldehyde oxidase have original inhibition.

Aldehyde oxidase, Xanthine oxidase, Electrochemical biosensor, Inhibition, nanocomposite