The effect of some antibiotics on glutathione reductase enzyme purified from liver and erythrocyte of Lake Van pearl mullet.

CONTEXT

The effect of antibiotics (amikacin, cefazolin, ivermectin, and kanamycin) on glutathione reductase (GR) isoenzymes activity in liver and erythrocyte of the fish, Chalcalburnus tarichi (Lake Van pearl mullet, Pallas 1811) (Cyprinidae) were investigated.

OBJECTIVE

This study determined the biochemical characterization of GR purified from the liver and erythrocytes of C. tarichi and the inhibition effect of the antibiotics on the GR isoenzymes.

MATERIALS AND METHODS

GR was purified by affinity chromatography from the tissues of C. tarichi. The biochemical characterization of GR such as optimum temperature, optimum pH, and ionic strength were determined. The inhibition effects of the antibiotics on the isoenzymes were evaluated as IC50 and Ki values. Ki constant and 50% inhibitory concentration (IC50) value for antibiotics were determined by Lineweaver-Burk graphs and plotting activity % versus [I], respectively, at five different concentrations of antibiotics.

RESULTS

Optimum temperature, pH, and ionic strength were determined for isoenzymes as 40 °C, 60 °C; 8.0, 8.0, and 50, 50 mM, respectively. Subunit molecular weights of the isoenzymes were estimated as 55 kDa by sodium dodecyl sulfate polyacrilamide gel electrophoresis (SDS-PAGE). In addition, IC50 and Ki values were calculated for amikacin, cefazolin, ivermectin, and kanamycin. The antibiotics showed non-competitive inhibition effects. IC50 values were calculated as 16.3, 36.6, 0.504, and 18.8 mM for liver and 20.0, 30.4, 0.787, and 31.8 mM for erythrocyte, respectively. Ki constants were 13.9, 18.4, 0.654, and 11.2 mM for liver and 23.2, 46.4, 1.19, and 36.4 mM for erythrocyte, respectively.

DISCUSSION AND CONCLUSION

The results indicated that the antibiotics displayed non-competitive inhibition.