A CHLOROPEROXIDASE-LIKE CATALYST IN SOIL - DETECTION AND CHARACTERIZATION OF SOME PROPERTIES

The objectives of the present study were: (i) to evaluate methods for detection of low rates of chloroperoxidase activity in aqueous solutions; (ii) to investigate the ability of soil extracts to catalyze chlorination; (iii) to investigate if the catalyzing ability of soil extracts is due to enzymatic activity. Initially, solutions of a commercially-available chloroperoxidase (EC 1.11.1.10, CPO) were studied, and it was found that chlorination of monochlorodimedone (MCD) and anisole followed by ps chomatographic analysis of chlorinated reaction products represented sensitive assay methods for determination of chloroperoxidase activity. Using these methods, eight out of nine soil extracts, obtained by performing a modified peroxidase extraction procedure, were found to catalyze chlorination. Further experimentation provided the following information: (i) the reaction did not proceed in the absence of hydrogen peroxide; (ii) the catalyst had a molecular weight larger than 10,000; (iii) the incorporation of chlorine was strongly pH-dependent, with an optimum at pH 3.0-3.5; (iv) the reaction was inhibited by orcinol, resorcinol and phloroglucinol. All these properties are similar to those of the commercial chloroperoxidase. It was therefore concluded that a chloroperoxidase-like catalyst was present in the investigated soils.