Purification and biochemical characterization of catalase that confers protection against hydrogen peroxide induced by stressful desert environment: the kidney catalase.

Camel is continually exposed to stressful desert environment that enhances generation of reactive oxygen species, including hydrogen peroxide (HO). Catalase plays an important role in detoxification of HO. A highly active catalase from camel kidney was purified to homogeneity, with a specific activity of 1,774,392 U/mg protein, using ion exchange and metal chelate affinity chromatography. The molecular weight of the enzyme was 268 kDa consisting of four identical subunits of 63 kDa. The enzyme showed higher optimum temperature (45 °C) and higher activation energy (4.37 kJ mol). The thermodynamic parameters, ΔH, ΔG and ΔS, were determined. The effect of various metal ions and chemicals on enzyme activity was investigated. , , and / values for HO were found to be 46 mM, 10,715,045 U/mg, 48,265,968 s and 2,966,562 smM, respectively. Camel kidney catalase displayed higher affinity efficiency for HO and can protect reduced glutathione (GSH) from oxidation by HO. Sodium azide was found to be a noncompetitive inhibitor of enzyme with and IC of 17.88 µM and 20.94 µM, respectively. Camel catalase showed unique biochemical properties. Interestingly, camel catalase can protect molecules (GSH) and organ functions (kidney) from the toxic effects of HO induced by stressful desert environment.