Catalase
Catalase (CAT) catalyzes the conversion of hydrogen peroxide to water and oxygen. CAT contains porphyrin-heme Fe group which reacts with the hydrogen peroxide. CAT containing Mn are called pseudocatalase (PCAT). Catalase-peroxidase (CAT KatG) is a bifunctional enzyme with both catalase and peroxidase activities. CAT KatG cofactor is a heme group. It provides defense against oxidative stress by reducing hydrogen peroxide. Mutations in CAT KatG can cause resistance to the anti-malarial drug isoniazid (INH). Catalase-phenol oxidase (CATPO) is a heme-containing CAT which shows phenol oxidase activity.
Catalase is a tetramer of four polypeptide chains, each over 500 amino acids long.[3] It contains four porphyrin heme (iron) groups that allow the enzyme to react with the hydrogen peroxide.
As hydrogen peroxide enters the active site, it interacts with the amino acids Asn147 (asparagine at position 147) and His74, causing a proton (hydrogen ion) to transfer between the oxygen atoms. The free oxygen atom coordinates, freeing the newly formed water molecule and Fe(IV)=O. Fe(IV)=O reacts with a second hydrogen peroxide molecule to reform Fe(III)-E and produce water and oxygen.[13] The reactivity of the iron center may be improved by the presence of the phenolate ligand of Tyr357 in the fifth iron ligand, which can assist in the oxidation of the Fe(III) to Fe(IV). The efficiency of the reaction may also be improved by the interactions of His74 and Asn147 with reaction intermediates.[13]
3D Structures of catalase3D Structures of catalase
Updated on 10-February-2014
1qqw, 1dgb, 1dgf, 1f4j – hCAT - human
4cat – CAT – Penicillium janthinellum
1iph, 1gge, 1ye9, 4bfi – EcCAT Hpii – Escherichia coli
1u2j, 1u2k – EcCAT Hpi C terminal
1u2l – EcCAT KatG
1cf9, 1qf7, 1gg9, 1ggh, 1ggj, 1ggk, 1p7y, 1p7z, 1p80, 1p81, 1qws, 3p9p, 3p9q, 3p9r, 3p9s, 3pq2, 3pq3, 3pq4, 3pq5, 3pq6, 3pq7, 3pq8, 3ttt, 3ttu, 3ttv, 3ttw, 3ttx, 4enp, 4enq, 4enr, 4ens, 4ent, 4enu, 4env, 4enw - EcCAT Hpii (mutant)
4blc, 1tgu, 1th3, 3nwl – bCAT – Bovine
1a4e – CAT A – yeast
2cag, 1e93, 1m85, 1mqf, 1h7k – PmCAT – Proteus mirabilis
1hbz, 1gwe, 1gwf – MlCAT – Micrococcus lysodeikticus
1m7s – CAT CatF – Pseudomonas syringae
1qwl, 2iqf – HpCAT – Helicobacter pylori
1si8 – CAT – Enterococcus Faecalis
1sj2, 2cca – MtCAT – Mycobacterium tuberculosis
2ccd - MtCAT KatG (mutant)
1ub2 – CAT – Synechococcus elongatus
1mwv, 2b2o, 2b2q, 2fxg, 2fxh, 2fxj – BpCAT KatG – Burkholderia pseudomallei
1x7u, 2dv1, 2dv2, 3n3r - BpCAT KatG (mutant)
1itk, 2a9e, 3n3s – CAT – Haloarcula marismortui
1sy7 – NcCAT-1 – Neurospora crassa
3ej6, 3zj4, 3zj5, 4aj9, 4bim – NcCAT-3
2j2m – CAT – Exiguobacterium oxidotolerans
2isa – CAT – Vibrio salmonicida
2xf2 - 2iuf – PjCAT – Penicillium janthinellum
2xq1 – CAT – Pichia angusta
4e37 – CAT – Pseudomonas aeruginosa
Catalase binary complexesCatalase binary complexes
2cah - PmCAT + NADPH
1gwh - MlCAT + NADPH
3n3o - BpCAT KatG + NAD
1nm0 – PmCAT + formiate
1qwm - HpCAT + formic acid
1dgg – hCAT + CN
1th2 – bCAT + N3
3rgs – bCAT + NH3
2iuf – PjCAT + O
3n3n - BpCAT KatG + INH
3n3p - BpCAT KatG + INH + AMP
3n3q - BpCAT KatG + INH
3n3h - BpCAT KatG (mutant) + INH
1dgh – hCAT + amino-triazole
1th4 - bCAT + amino-triazole
1ggf - EcCAT HPII (mutant) + H2O2
Pseudocatalase Mn-containingPseudocatalase Mn-containing
1jku – LpPCAT-Mn – Lactobacillus plantarum
1o9i – LpPCAT-Mn (mutant)
2cwl – TtPCAT-Mn Mn-free – Thermus thermophilus
2v8u - TtPCAT-Mn
2v8t - TtPCAT-Mn + chloride
1jkv - LpPCAT-Mn + N3
Catalase-phenol oxidaseCatalase-phenol oxidase
4aue, 4aul, 4aum, 4aun, 4b2y, 4b31, 4b40, 4b5k - CATPO - Scytalidium thermophilum