View source for Catalase

{{split}}
{{Pfam_box
| Symbol = cat
| Name = Catalase
| image =
| width =
| caption =
| Pfam= PF00199
| InterPro= IPR011614
| SMART=
| PROSITE = PDOC00395
| SCOP = 7cat
| TCDB =
}}
<!-- The GNF_Protein_box is automatically maintained by Protein Box Bot.  See Template:PBB_Controls to Stop updates. -->
{{GNF_Protein_box
 | image = PBB_Protein_CAT_image.jpg
 | image_source = [[Protein_Data_Bank|PDB]] rendering based on 1dgb.
 | PDB = {{PDB2|1dgb}}, {{PDB2|1dgf}}, {{PDB2|1dgg}}, {{PDB2|1dgh}}, {{PDB2|1f4j}}, {{PDB2|1qqw}}, {{PDB2|1tgu}}, {{PDB2|1th2}}, {{PDB2|1th3}}, {{PDB2|1th4}}, {{PDB2|4blc}}, {{PDB2|7cat}}, {{PDB2|8cat}}
 | Name = Catalase
 | HGNCid = 1516
 | Symbol = CAT
 | AltSymbols =; MGC138422; MGC138424
 | OMIM = 115500
 | ECnumber =  1.11.1.6
 | Homologene = 55514
 | MGIid = 88271
 | GeneAtlas_image1 = PBB_GE_CAT_201432_at_tn.png
 | GeneAtlas_image2 = PBB_GE_CAT_211922_s_at_tn.png
 | Function = {{GNF_GO|id=GO:0004096 |text = catalase activity}} {{GNF_GO|id=GO:0005506 |text = iron ion binding}} {{GNF_GO|id=GO:0046872 |text = metal ion binding}} 
 | Component = {{GNF_GO|id=GO:0005739 |text = mitochondrion}} {{GNF_GO|id=GO:0005777 |text = peroxisome}} {{GNF_GO|id=GO:0005778 |text = peroxisomal membrane}} 
 | Process = {{GNF_GO|id=GO:0006118 |text = electron transport}} {{GNF_GO|id=GO:0006979 |text = response to oxidative stress}} {{GNF_GO|id=GO:0042744 |text = hydrogen peroxide catabolic process}} 
 | Orthologs = {{GNF_Ortholog_box
    | Hs_EntrezGene = 847
    | Hs_Ensembl = ENSG00000121691
    | Hs_RefseqProtein = NP_001743
    | Hs_RefseqmRNA = NM_001752
    | Hs_GenLoc_db =  
    | Hs_GenLoc_chr = 11
    | Hs_GenLoc_start = 34417054
    | Hs_GenLoc_end = 34450176
    | Hs_Uniprot = P04040
    | Mm_EntrezGene = 12359
    | Mm_Ensembl = ENSMUSG00000027187
    | Mm_RefseqmRNA = NM_009804
    | Mm_RefseqProtein = NP_033934
    | Mm_GenLoc_db =  
    | Mm_GenLoc_chr = 2
    | Mm_GenLoc_start = 103254746
    | Mm_GenLoc_end = 103285962
    | Mm_Uniprot = Q3TVZ1
  }}
}}

{{SI}}

{{CMG}}



==Overview==
'''Catalase''' is a common [[enzyme]] found in nearly all living organisms. Its functions include [[catalyst|catalyzing]] the decomposition of [[hydrogen peroxide]] to [[water]] and [[oxygen]].<ref name=UAH_1>{{cite web | title = Catalase: An Enzyme at Work| work = Science Education Outreach | url=http://crystal.uah.edu/~carter/enzyme/catalase.htm | accessdate=2007-02-11}}</ref> Catalase has one of the highest turnover rates of all enzymes; one molecule of catalase can convert millions of molecules of hydrogen peroxide to water and oxygen per second.<ref>{{cite web | title = Catalase | work = Molecule of the Month | publisher = RCSB Protein Data Bank | url = http://www.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb57_1.html | date = 2004-09-01 | accessdate = 2007-02-11}}</ref>

Catalase is a [[tetramer]] of four polypeptide chains, each over 500 amino acids long.<ref name=Boon_a>{{cite web | author = Boon EM, Downs A, Marcey D |title = Catalase: H<sub>2</sub>O<sub>2</sub>: H<sub>2</sub>O<sub>2</sub> Oxidoreductase | work = Catalase Structural Tutorial Text | url = http://biology.kenyon.edu/BMB/Chime/catalase/frames/cattx.htm | accessdate = 2007-02-11}}</ref> It contains four [[porphyrin]] [[heme]] (iron) groups that allow the enzyme to react with the hydrogen peroxide. The optimum [[pH]] for catalase is approximately (pH 7.0),<ref name=Maehly_1954>{{cite book | authors = Maehly A, Chance B | title = The Assay of Catalases and Peroxidases ''in'' Methods of Biochemical Analysis | pages = 357 | year = 1954 | id = ISBN }}</ref> while the optimum temperature varies by species.<ref name=Bucknell>{{cite web | title = A Quantitative Enzyme Study; CATALASE | url = http://web.archive.org/web/20000612104029/http://www.facstaff.bucknell.edu/toner/gb/lab121/labs34.html | accessdate = 2007-02-11}}</ref>

==History==
Catalase was first noticed as a substance in [[1811]] when [[Louis Jacques Thénard]], who discovered H<sub>2</sub>O<sub>2</sub> (hydrogen peroxide), suggested that its breakdown is caused by a substance.

In [[1900]] [[Oscar Loew]] was the first to give it the name catalase, and found its presence in many plants and animals<ref>{{cite journal
|title=A New Enzyme of General Occurrence in Organisms
|author=Loew, Oscar
|journal=Science
|volume=11
|issue=279
|pages=701-2
|month=May
|year=1900
 | doi = 10.1126/science.11.279.701 <!--Retrieved from CrossRef by DOI bot-->
}}</ref>. In [[1937]] catalase from beef liver was crystallised by [[James B. Sumner]] <ref>{{cite journal
|journal=Science
|title=Cystalline Catalase
|author=Sumner, J.B.
|authorlink=James B. Sumner
|coauthors=Dounce, A. L.
|volume=87
|issue=18
|year=1938 | pages = 284
 | doi = 10.1126/science.87.2256.284 <!--Retrieved from CrossRef by DOI bot-->
}}</ref> and the molecular weight worked out in [[1938]]<ref>{{cite journal
|title=The Molecular Weight of Crystalline Catalase
|author=Sumner, James B.
|coauthors=Gralen, Nils
|journal=Science
|volume=87
|issue=2256
|pages=284
|month=Mar fart 
|year=1938 | doi = 10.1126/science.87.2256.284 <!--Retrieved from CrossRef by DOI bot-->
}}</ref>.
In [[1969]] the [[amino acid]] sequence of [[bovine]] catalase was worked out<ref>{{cite journal
|author=Schroeder WA
|coauthors=Shelton JR; Shelton JB; Robberson B; Apell G.	
|title=The amino acid sequence of bovine liver catalase: a preliminary report.
|journal=Arch Biochem Biophys
|year=1969
|month=May
|volume=131|issue=2|pages=653-5
|pmid=4892021
 | doi = 10.1016/0003-9861(69)90441-X <!--Retrieved from CrossRef by DOI bot-->
}}</ref>. Then in [[1981]], the 3D structure of the protein was revealed<ref>{{cite journal
|title=Structure of beef liver catalase.
|author=Murthy MR
|coauthors=Reid TJ 3rd; Sicignano A; Tanaka N; Rossmann MG.
|journal=J Mol Biol
|year=1981
|month=Oct
|volume=152|issue=2|pages=465-99
|pmid=7328661 
 | doi = 10.1016/0022-2836(81)90254-0 <!--Retrieved from CrossRef by DOI bot-->
}}</ref>.

==Action of catalase==
The reaction of catalase in the decomposition of hydrogen peroxide is:

: 2 H<sub>2</sub>O<sub>2</sub> → 2 H<sub>2</sub>O + O<sub>2</sub><ref name=UAH_2>{{cite web | title = Catalase: A Closer Look | work = Science Education Outreach | url=http://crystal.uah.edu/~carter/enzyme/closer.htm | accessdate=2007-02-11}}</ref>

In [[microbiology]], the ''catalase test'' is used to differentiate between [[bacteria]]l [[species]] in the lab.[http://www2.austin.cc.tx.us/microbugz/html/catalase_test.html] The test is done by placing a drop of hydrogen peroxide on a [[microscope slide]]. Using an applicator stick, a scientist touches the colony and then smears a sample into the hydrogen peroxide drop. If bubbles or froth forms, the organism is said to be ''catalase-positive''; if not, the organism is ''catalase-negative''.[http://dentistry.ouhsc.edu/intranet-web/courses/dmi_8351/Catalase.html] This test is particularly useful in distinguishing [[staphylococcus|staphylococci]] and [[micrococcus|micrococci]], which are catalase-positive, from [[streptococcus|streptococci]] and [[enterococcus|enterococci]], which are catalase-negative.[http://www2.austin.cc.tx.us/microbugz/html/catalase_test.html] While the catalase test alone cannot identify a particular organism, combined with other tests, it can aid diagnosis. The presence of catalase in bacterial cells depends on both the growth condition and the medium used to grow the cells.

==Molecular mechanism==
While the complete mechanism of catalase is not currently known, the [[chemical reaction|reaction]] is believed to occur in two stages:

: H<sub>2</sub>O<sub>2</sub> + Fe(III)-E → H<sub>2</sub>O + O=Fe(IV)-E(.+)

: H<sub>2</sub>O<sub>2</sub> + O=Fe(IV)-E(.+) → H<sub>2</sub>O + Fe(III)-E + O<sub>2</sub><ref name=Boon_b>{{cite web | author = Boon EM, Downs A, Marcey D | title = Proposed Mechanism of Catalase ''in'' Catalase: H<sub>2</sub>O<sub>2</sub>: H<sub>2</sub>O<sub>2</sub> Oxidoreductase | work = Catalase Structural Tutorial Text | url = http://biology.kenyon.edu/BMB/Chime/catalase/frames/cattx.htm#Proposed%20Mechanism%20of%20Catalase | accessdate = 2007-02-11}}</ref>

:Here Fe()-E represents the [[iron]] centre of the [[heme]] group attached to the enzyme. Fe(IV)-E(.+) ís a mesomeric form of Fe(V)-E, meaning that iron is not completely oxidized to +V but receives some "supporting electron" from the heme ligand. This heme has to be drawn then als radical cation (.+).

As hydrogen peroxide enters the [[active site]], it interacts with the [[amino acid]]s Asn147 ([[asparagine]] at position 147) and [[histidine|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.<ref name=Boon_b /> The reactivity of the iron center may be improved by the presence of the phenolate [[ligand]] of [[tyrosine|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]].<ref name=Boon_b /> In general, the rate of the reaction can be determined by the [[Michaelis-Menten equation]].[http://www.madsci.org/posts/archives/aug98/900981784.Bc.r.html]

Catalase can also oxidize different toxins, such as [[formaldehyde]], [[formic acid]], and [[alcohols]]. In doing so, it uses [[hydrogen peroxide]] according to the following reaction:

: H<sub>2</sub>O<sub>2</sub> + H<sub>2</sub>R → 2H<sub>2</sub>O + R

Again, the exact mechanism of this reaction is not known.

Any heavy metal ion (such as copper cations in [[copper(II) sulfate]]) will act as a [[noncompetitive inhibitor]] on catalase. Also, the poison [[cyanide]] is a [[competitive inhibitor]] of catalase, strongly binding to the [[heme]] of catalase and stopping the enzyme's action.

Three-dimensional [[protein structure]]s of the peroxidated catalase intermediates are available at the [[Protein Data Bank]]. This enzyme is commonly used in laboratories as a tool for learning the effect of enzymes upon reaction rates.

==Cellular role==
Hydrogen peroxide is a harmful by-product of many normal [[metabolism|metabolic]] processes: To prevent damage, it must be quickly converted into other, less dangerous substances. To this end, catalase is frequently used by cells to rapidly catalyze the [[Chemical decomposition|decomposition]] of hydrogen peroxide into less reactive [[gas]]eous [[oxygen]] and water molecules.<ref name=Gaetani_1996>{{cite journal | author = Gaetani G, Ferraris A, Rolfo M, Mangerini R, Arena S, Kirkman H | title = Predominant role of catalase in the disposal of hydrogen peroxide within human erythrocytes. | journal = Blood | volume = 87 | issue = 4 | pages = 1595-9 | year = 1996 | id = PMID 8608252}}</ref>

The true biological significance of catalase is not always straightforward to assess: Mice genetically engineered to lack catalase are phenotypically normal, indicating that this enzyme is dispensable in animals under some conditions.<ref name=Ho_2004>{{cite journal | author = Ho YS, Xiong Y, Ma W, Spector A, Ho D | title = Mice Lacking Catalase Develop Normally but Show Differential Sensitivity to Oxidant Tissue Injury. | journal = J Biol Chem | volume = 279 | issue = 31 | pages = 32804-812 | year = 2004 | id = PMID 15178682 | doi = 10.1074/jbc.M404800200 <!--Retrieved from CrossRef by DOI bot-->}}</ref>

Some human beings have very low levels of catalase ([[acatalesimia]]), yet show few ill effects. It is likely that the predominant scavengers of H2O2 in normal mammalian cells are [[preoxiredoxins]] rather than catalase.

Catalase works at an optimum temperature of 37 °C, which is approximately the temperature of the human body.

Catalase is usually located in a cellular [[organelle]] called the [[peroxisome]].<ref name=MBOC>{{cite book | author = Alberts B, Johnson A, Lewis J, Raff M, Roberts K, Walter P | title = Peroxisomes, ''in'' ''Molecular Biology of the Cell'' | edition = 4th ed. | publisher = Garland | year = 2002 | id = [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Search&db=books&doptcmdl=GenBookHL&term=catalase+AND+mboc4%5Bbook%5D+AND+373476%5Buid%5D&rid=mboc4.section.2194 (via NCBI Bookshelf)] ISBN 0815332181}}</ref> Peroxisomes in plant cells are involved in [[photorespiration]] (the use of oxygen and production of carbon dioxide) and symbiotic [[nitrogen fixation]] (the breaking apart of [[diatomic]] [[nitrogen]] (N<sub>2</sub>) to reactive nitrogen atoms).

Hydrogen peroxide is used as a potent antimicrobial agent when cells are infected with a pathogen. Pathogens that are catalase-positive, such as ''[[Mycobacterium tuberculosis]]'', ''[[Legionella pneumophila]]'', and ''[[Campylobacter jejuni]]'', make catalase in order to deactivate the peroxide radicals, thus allowing them to survive unharmed within the [[Host (biology)|host ]].[http://mic.sgmjournals.org/cgi/content/full/149/9/2635]

==Distribution among organisms==
All known [[animals]] use catalase in every [[organ (anatomy)|organ]], with particularly high concentrations occurring in the [[liver]]. One unique use of catalase occurs in [[bombardier beetle]]. The beetle has two sets of chemicals ordinarily stored separately in its paired glands. The larger of the pair, the storage chamber or reservoir, contains [[hydroquinone]]s and [[hydrogen peroxide]], whereas the smaller of the pair, the reaction chamber, contains catalases and [[peroxidase]]s. To activate the spray, the beetle mixes the contents of the two compartments, causing oxygen to be liberated from hydrogen peroxide. The oxygen oxidizes the hydroquinones and also acts as the propellant. <REF>{{cite journal| pmid = 10449758 | title = Spray aiming in the bombardier beetle: photographic evidence. | author =     T Eisner and DJ Aneshansley | journal =  Proc Natl Acad Sci U S A | date = 1999 Aug | volume = 96 | issue = 17 | pages = 9705-9}}</REF> 

Catalase is also universal among [[plants]], but not among [[fungi]], although some species have been found to produce the enzyme when growing in an environment with a low pH and warm temperatures.<ref>{{cite journal| pmid = 16503295 | title = Production of catalase by fungi growing at low pH and high temperature. | author = K. Isobe, et al. | journal =  J Biosci Bioeng | date = 2006 Jan | volume = 101 | issue = 1 | pages = 73-6 | doi = 10.1263/jbb.101.73 <!--Retrieved from CrossRef by DOI bot-->}}</ref> 

Very few [[aerobic microorganisms]] are known that do not use catalase. [http://madsci.org/posts/archives/jun99/929507203.Gb.r.html]. ''Streptococcus'' species are an example of aerobic bacteria that do not possess catalase. Catalase has also been observed in some [[anaerobic]] [[microorganisms]], such as [[Methanosarcina barkeri]].<ref>{{cite journal | doi = 10.1099/mic.0.28542-0 | title = The catalase and superoxide dismutase genes are transcriptionally up-regulated upon oxidative stress in the strictly anaerobic archaeon Methanosarcina barkeri. | author = Andrei Brioukhanov, Alexander Netrusov, and Rik Eggen. | journal = [[Microbiology (journal)|Microbiology]] | volume = 152 | pages = 1671 - 1677 | year = 2006}}</ref>

==Human applications==
[[Image:Hydrogen-peroxide-2D.png|left|thumb|Hydrogen peroxide]]
Catalase is used in the food industry for removing [[hydrogen peroxide]] from [[milk]] prior to [[cheese production]].[http://www.worthington-biochem.com/CTL/default.html] Another use is in [[food wrappers]], where it prevents food from [[oxidation|oxidizing]].[http://madsci.org/posts/archives/mar99/921636249.Gb.r.html] Catalase is also used in the [[textile]] industry, removing hydrogen peroxide from fabrics to make sure the material is peroxide-free.[http://www.p2pays.org/ref/11/10842.htm] A minor use is in [[contact lens]] hygiene - a few lens-cleaning products [[disinfection|disinfect]] the lens using a hydrogen peroxide solution; a solution containing catalase is then used to decompose the hydrogen peroxide before the lens is used again.<ref>{{US patent|5521091}}</ref> Recently, catalase has also begun to be used in the aesthetics industry. Several mask treatments combine the enzyme with hydrogen peroxide on the face with the intent of increasing cellular oxygenation in the upper layers of the [[Epidermis (skin)|epidermis]].
{{-}}

==Pathology==
The [[peroxisomal disorder]] [[acatalasia]] is due to a deficiency in the function of catalase.

== See also ==
* [[Enzyme kinetics]]
* [[Peroxidases]]
* [[Superoxide dismutase]]</s>

==References==
{{Reflist|2}}

==External links==
* [http://genomics.senescence.info/genes/entry.php?hugo=CAT CAT] at the GenAge database.
* [http://www.seps.org/cvoracle/faq/catalase.html Catalase FAQ]
* [http://madsci.org/FAQs/catalase.html Catalase Enzymatics, Expression and Applications ''MadSci Network'']
* [http://www.tgw1916.net/movies.html Bacteria catalase test video]

{{Peroxidases}}

[[Category:EC 1.11.1]]
[[Category:Antioxidants]]
[[Category:Hemoproteins]]
[[Category:Enzymes]]

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[[ar:كتالاز]]
[[ca:Catalasa]]
[[cs:Kataláza]]
[[de:Katalase]]
[[es:Catalasa]]
[[eu:Katalasa]]
[[fr:Catalase]]
[[it:Catalasi]]
[[nl:Katalase]]
[[ja:カタラーゼ]]
[[pl:Katalaza]]
[[pt:Catalase]]
[[ru:Каталаза]]
[[sl:Katalaza]]
[[sr:Каталаза]]
[[sv:Katalas]]
[[uk:Каталаза]]
[[zh:过氧化氢酶]]

for systematic sequence analysis of catalases AND peroxidases
see http://peroxibase.isb-sib.ch/