PURIFICATION AND PARTIAL CHARACTERIZATION OF LIVER CATALASE FROM CONTROL AND Pb+Cd METAL MIXTURE STRESSED Oreochromis niloticus.

Water contamination is a severe environmental issue and has worse effects on fish health. Antioxidant system is present in all living organisms that maintain redox homeostasis by neutralizing reactive oxygen species (ROS). Catalase (CAT) is the part of antioxidant system that protect an organism from oxidative stress by detoxifying H2O2 into H2O and O2 molecule. Majority of enzymes are intermingled with other biomolecules when extracted and needed to purify so that biochemical properties can be described clearly. The first purpose of the present research work was to investigate whether tilapia produce more CAT in the chronic metal mixture stressed condition or not. While, the second purpose of the present research work was to purify and partially characterize the liver CAT from control and Pb+Cd metal mixture stressed Oreochromis niloticus. The inferences of present study showed higher liver CAT activity in control O. niloticus as compared to binary metal mixture treated O. niloticus. Significant differences (p<0.05) were observed when compared liver CAT activity among control and stressed fish. Specific activity of purified liver CAT was observed 1027.52 and 946.93 Umg-1 for control and metal stressed fish, respectively. The fold purification of control and metal treated fish liver CAT was recorded 15.27 and 15.44, respectively. Optimum pH and temperature of liver CAT purified from both control and metal stressed fish was found 7 and 25°C. Km value for control and metal stressed O. niloticus liver was measured 6.82 and 1.71mM H2O2mL-1, respectively. On the basis of present study inferences, it is concluded that chronic Pb+Cd metal mixture stress condition did not improve the yield of liver CAT but inhibited in O. niloticus. [ABSTRACT FROM AUTHOR]