Biochemical Characterization of Catalase from Liver of Variola louti Collected from Reference and Polluted Areas in Jeddah Red Sea Coast

The aim of the present study is to compare the biochemical properties of catalase (CAT) from liver of Variolalouticollected frompolluted and reference areasin Jeddah southern Red Sea coast. The two enzymes had the same stability at pH 7.5. The CAT activity from polluted area was higher in the two sides of pH profile than that of reference area. The CAT activity from reference and polluted areas were approximately stable up to 40 °C. The CAT activity from reference and polluted area retained 46 and 88% of their activities at 50°C, respectively. The Km values of CAT in reference and polluted areas were 37 and 50 mMH2O2, respectively. The results indicated that CAT at reference area had higher affinity toward H2O2 than that at polluted area. Ca2+ had no inhibitory effect on CAT activity at reference and polluted areas. Ni2+, Zn2+ and Co2+ caused the same partially inhibitory effect on CAT at reference and polluted areas. Complete loss of CAT activity was detected in presence of Hg2+. CAT from polluted area was more stable when exposed to 5 and 10 % N-butanol, isopropanol, dioxan and heptanol than that in reference area. The CAT from polluted area was markedly more stable against Triton X-100 and Tween-20 than that in reference area. No significant effect of urea atconcentration of 2 and 4 M on CATat reference and polluted areas was detected. The results indicated that CAT from polluted area had more resistance against physical and chemical conditions than those in reference area.