PROSITE documentation PDOC00395

Catalase signatures and profile

Catalase (EC 1.11.1.6) [1,2,3] or more correctly, hydroperoxidase [4] is a heme-containing enzyme, present in all aerobic cells, that decomposes hydrogen peroxide to molecular oxygen and water. Its main function is to protect cells from the toxic effects of hydrogen peroxide. In eukaryotic organisms and in some prokaryotes catalase is a molecule composed of four identical subunits. Each of the subunits binds one protoheme IX group.

The typical core catalase is composed of a heme-containing active site deeply buried in a β-barrel structure with two or three channels providing access to the heme (see <PDB:1A4E>) [5]. A conserved tyrosine serves as the heme proximal side ligand. We have used the region around this residue as a first signature pattern; it also includes a conserved arginine that participates in heme-binding. A conserved histidine has been shown to be important for the catalytic mechanism of the enzyme. We have used the region around this residue as a second signature pattern. We also developed a profile which covers the whole conserved region.