A review of structural properties, metabolic function and measurement of peroxidase activity

The production of reactive oxygen species occurs during the natural metabolism of oxidative-breathing cells. Among reactive oxygen species, hydrogen peroxide is more dangerous to cell life due to its long half-life, but it is meanwhile an important regulatory molecule in redox signaling in living things. Peroxidases are one of the key antioxidant enzymes that are widely distributed in nature and promote the oxidation of various electron donor substrates simultaneously with the decomposition of hydrogen peroxide and produce water during reducing hydrogen peroxide and other hydroperoxides. Peroxidases, in addition to their known peroxide inhibitory properties, also have physiological oxidizing functions.Based on the chemistry of the active site in the interaction with the peroxide, peroxidases are classified to non-heme and heme bearing peroxidases. The former contains heme in its catalytic center, and the latter has a reactive selenol or thiol in its active site. Iron-based plant peroxidases are divided into three classes I, II and III. Thiol plant peroxidases include glutathione peroxidase and proxy reduxins. The present article explains the structural and metabolic, and properties of peroxidases and provides certain practical procedures for determination of their enzymatic activities.