Comparison of peroxidases from barley kernel (Hordeum vulgare L.) and wheat germ (Triticum aestivum L.):: Isolation and preliminary characterization

Peroxidases (POD) of crude extracts from barley and wheat germ were separated, partially purified using salt fractionation, ion-exchange and hydrophobic interaction chromatographies and their properties examined. Barley and wheat germ POD contained basic, neutral and anionic isoforms as confirmed by isoelectricfocusing. Toyopearl-Butyl 650 M chromatography resolved POD into four cationic fractions. Chromatography of wheat gem extract on CM-Sepharose isolated an anionic and a neutral fraction. Following chromatography on Concanavalin-A Sepharose, enzymes from both cereals showed differences in their elution properties. Optimum pH ranges were 4.0 to 5.5 (barley) and 5.3 to > 6.3 (wheat gem) and POD reacted differently under acidic or basic conditions. Their catalytic behavior in the presence of calcium also differed, Kinetics of POD were of Michaelian type with a ping-pong mechanism and Michaelis constants of guaiacol oxidation in the presence of hydrogen peroxide varied from one enzymatic group to another.