Humpath.com - Human pathology

Home > A. Molecular pathology > catalase

catalase

Wednesday 8 February 2006

Catalase is a common enzyme found in living organisms. Its functions include catalyzing the decomposition of hydrogen peroxide to water and oxygen.

Catalase has one of the highest turnover rates for all enzymes; one molecule of catalase can convert 6 million molecules of hydrogen peroxide to water and oxygen each minute.

Catalase is a tetramer of 4 polypeptide chains which are at least 500 amino acids in length. Within this tetramer there are 4 porphyrin haem (iron) groups which are what allows it to react with the hydrogen peroxide. It’s optimum pH is in the alkaline range.

Hydrogen peroxide is formed as a waste product of metabolism in many living organisms. It is toxic and must be quickly converted into other, less dangerous, chemicals. To manage this problem, the enzyme catalase is frequently used to rapidly catalyse the decomposition of hydrogen peroxide into harmless oxygen and water.

Hydrogen peroxide is used as a potent antimicrobial agent when cells are infected with a pathogen. Pathogens that are catalase positive make catalase in order to deactivate the peroxide radicals, thus allowing them to survive unharmed in the host cell.

In cells, catalase is present in peroxisomes and decomposes H2O2 (2 H2O2 → O2 + 2 H2O).