| Literature References | 1. NI, W.T. AND TRELEASE, R.N.
Two genes encode the two subunits of cottonseed catalase.
ARCH.BIOCHEM.BIOPHYS. 289 237-243 (1991).
2. MURTHY, M.R.N., REID, T.J., SICIGNANO, A., TANAKA, N. AND ROSSMANN, M.
Structure of beef liver catalase.
J.MOL.BIOL. 152 465-499 (1981).
3. VON OSSOWSKI, I., MULVEY, M.R., LECO, P.A., BORYS, A. AND LOEWEN, P.C.
Nucleotide sequence of Escherichia coli katE, which encodes catalase HPII.
J.BACTERIOL. 173(2) 514-520 (1991).
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| Documentation | Catalase is a constitutive peroxisomal enzyme [1] that catalyses the
conversion of hydrogen peroxide to water and molecular oxygen in a
`catalatic' reaction, which protects the cell from the toxic effects of
hydrogen peroxide [2]. It can also oxidise a number of other compounds in
the presence of hydrogen peroxide in a `peroxidatic' reaction [2], which
is responsible for ethanol oxidation in liver, if the concentration of
hydrogen peroxide is high enough. Different catalase isoforms can be
identified within a particular species, the number of isoforms ranging
from 1 in lentil cotyledons to 12 in mustard cotyledons [1]. Most catalases
exist as tetramers of 65kDa subunits, each subunit containing a protohaem
IX group [3] buried deep within the structure, but which is accessible
through hydrophobic channels [2].
CATALASE is a 7-element fingerprint that provides a signature for the
catalases. The fingerprint was derived from an initial alignment of 6
sequences: motifs 2 and 7 include regions encoded by PROSITE patterns
CATALASE_2 (PS00438) and CATALASE_1 (PS00437), the former containing a
highly conserved His thought to be important for catalysis, the latter
including the Tyr that acts as the proximal ligand for the haem iron atom.
Two iterations on OWL21.1 were required to reach convergence, at which
point a true set comprising 38 sequences was identified. A single partial
match was also found, a catalase fragment.
An update on SPTR37_9f identified a true set of 106 sequences.
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