Purification and characterization of glucose-6phosphate dehydrogenase from Eisenia fetida and effects of some pesticides and metal ions

Abstract

Objectives: Earthworms have a large impact on the soil ecosystem. They are quite sensitive to pollutants. Purification and biochemical characterization of glucose-6phosphate dehydrogenases (G6PD) from the earthworm species Eisenia fetida were aimed. The determination of the toxicity potentials of some soil pollutants on G6PD activity was intended. Methods: G6PD was isolated using 2′,5′-ADP-Sepharose 4B affinity column. Enzyme purity and molecular mass were determined by SDS-PAGE. Its biochemical properties investigated. The effects of some soil pollutants on the enzyme were studied in vitro. Results: Enzyme was purified with 28% yields and 232 fold. Optimum pH and buffer concentration, optimal and stable temperature was determined as pH: 8.5, 60 mM, 25 °C and 20 °C. Its molecular weight estimated as 36 kDa. The Ni2+, Hg2+, Pb2+, Cr2+, and Fe2+ ions with IC50 values in the range of 56 ± 06-120 ± 20 μM and the diniconazole, metalaxyl, methomyl, carboxyl, and oxamyl with IC50 values in the range of 7.6 ± 1.2-77 ± 12 μM exhibited an inhibitory effect on G6PD. Conclusions: G6PD was isolated and characterized from E. fetida. Its catalytic activity decreased with very low concentration by pesticides and metal ions. The results indicated that the inhibition of G6PD may be important in the toxicity mechanism of pollutants on this earthworm.