Catalase

Wasserstoffperoxid

Catalase reaction

Catalase is an enzyme that plays a crucial role in the protection of the cellular organelles from oxidative damage by reactive oxygen species (ROS). It catalyzes the decomposition of hydrogen peroxide to water and oxygen, a critical reaction in the cells of nearly all living organisms exposed to oxygen. This enzyme is present in the peroxisomes of cells, which are involved in the metabolism of fatty acids and the detoxification of hydrogen peroxide.

Function

Catalase has one of the highest turnover numbers of all enzymes; one catalase molecule can convert millions of hydrogen peroxide molecules to water and oxygen each second. Hydrogen peroxide is a harmful by-product of many normal metabolic processes: to prevent damage, it must be quickly converted into other, less dangerous substances. By efficiently removing hydrogen peroxide, catalase allows cellular metabolic processes to proceed with minimal oxidative damage.

Structure

Catalase is a tetramer of four polypeptide chains, each over 500 amino acids long. It contains four iron-containing heme groups that allow the enzyme to react with the hydrogen peroxide. The structure of catalase is highly conserved across different species, indicating its essential role in life.

Biological Role

Beyond its fundamental role in detoxifying hydrogen peroxide, catalase also has various other biological functions. It is involved in the signaling pathways related to the oxidative stress response and is implicated in some plant defense mechanisms. In humans and other animals, catalase deficiency can lead to a variety of health issues, including the rare genetic disorder acatalasemia, which involves the complete absence of catalase activity.

Clinical Significance

In medicine, catalase activity is a diagnostic marker for certain diseases and conditions. For example, a lack of catalase can lead to an accumulation of hydrogen peroxide in the body, causing damage to tissues and contributing to the development of diabetes, atherosclerosis, and other diseases. Additionally, the study of catalase has implications for cancer research, as cancer cells often exhibit altered catalase activity.

Applications

Catalase has industrial applications, including its use in the textile industry to remove hydrogen peroxide from fabrics after bleaching and in the food industry to prevent the oxidation of food. In scientific research, catalase activity is a common assay for the presence of blood and the quantification of bacterial load.

See Also

• Enzyme
• Hydrogen peroxide
• Oxidative stress
• Peroxisome