Catalase (EC 126.96.36.199) [1,2,3] or more correctly, hydroperoxidase  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>) . 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.
Some prokaryotic catalases belong to the non-animal heme peroxidase
family (see <PDOC00394>).
August 2008 / Profile added and text revised.
PROSITE methods (with tools and information) covered by this documentation:
Murthy M.R.N. Reid T.J. III Sicignano A. Tanaka N. Rossmann M.G.
PROSITE is copyright. It is produced by the SIB Swiss Institute
Bioinformatics. There are no restrictions on its use by non-profit
institutions as long as its content is in no way modified. Usage by and
for commercial entities requires a license agreement. For information
about the licensing scheme send an email to
or see: prosite_license.html.