Encyclopedia > Catalase

  Article Content


Catalase (human erythrocyte catalase: PDB 1DGF (http://www.rcsb.org/pdb/cgi/explore.cgi?pid=166031034358435&page=0&pdbId=1DGF), EC is a common enzyme found in living organisms. Its functions include catalyzing the decomposition of hydrogen peroxide.

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. Catalase is mainly used in the textile industry, removing hydrogen peroxide from fabrics to make sure the material is peroxide free. A minor use is in contact lens hygiene - some lens cleaning systems sterilise the lenses by soaking them in a hydrogen peroxide solution, and catalase is used to decompose the peroxide before reinserting the lenses in the eye.

The complete mechanism of catalase is not yet known; however, the reaction occurs in two stages:

H2O2 + Fe(III)-E → H2O + O=Fe(IV)-E

H2O2 + O=Fe(IV)-E → H2O + Fe(III)-E

(Where Fe-E represents the iron centre of the heme group attached to the enzyme.)

As hydrogen peroxide enters the active site it is forced to interact with the amino acids His74 and Asn174. This causes a proton (hydrogen ion) to transfer from the first oxygen to the second, polarizing and stretching the O-O bond, which breaks heterolytically. The free oxygen atom coordinates with the iron centre of the active site, displacing the newly formed water molecule and forming Fe(IV)=O. In the second stage, the Fe(IV)=O reacts with another hydrogen peroxide to reform Fe(III)-E plus water and oxygen molecules.

3D Structures of the peroxidated catalase intermediates are available at the Protein Data Bank.

see also: peroxidases

External links

All Wikipedia text is available under the terms of the GNU Free Documentation License

  Search Encyclopedia

Search over one million articles, find something about almost anything!
  Featured Article
French resistance

... of the Spanish Civil War. Resistance groups also helped Allied pilots who had been shot down to get back to Britain. They minimized the threat of discovery by ...

This page was created in 37.3 ms