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cosa of ileum skin of hip skin of thigh top expressed in left lobe of liver blood proximal tubule tunica adventitia of aorta right kidney subcutaneous adipose tissue stroma of bone marrow brown adipose tissue human kidney intercostal muscle more reference expression data biogps more reference expression data gene ontology molecular function protein homodimerization activity aminoacylase activity peroxidase activity metal ion binding oxidoreductase activity acting on peroxide as acceptor catalase activity antioxidant activity heme binding nadp binding enzyme binding oxidoreductase activity signaling receptor binding identical protein binding cellular component cytosol golgi apparatus membrane intracellular membrane bounded organelle focal adhesion mitochondrial intermembrane space peroxisomal membrane peroxisome plasma membrane peroxisomal matrix endoplasmic reticulum mitochondrion lysosome extracellular exosome extracellular region extracellular space secretory granule lumen ficolin 1 rich granule lumen biological process response to phenylpropanoid ureteric bud development response to estradiol response to hypoxia response to cadmium ion response to fatty acid kidney development response to inactivity response to hyperoxia cellular response to growth factor stimulus ageing cholesterol metabolic process response to l ascorbic acid negative regulation of apoptotic process response to ozone response to oxidative stress response to activity protein tetramerization response to vitamin e response to insulin response to vitamin a aerobic dissimilation response to lead ion positive regulation of nf kappab transcription factor activity osteoblast differentiation hydrogen peroxide catabolic process uv protection positive regulation of phosphatidylinositol 3 kinase signaling response to radiation response to light intensity response to ethanol negative regulation of nf kappab transcription factor activity triglyceride metabolic process protein homotetramerization response to uv response to toxic substance response to hydrogen peroxide hemoglobin metabolic process positive regulation of cell division cellular oxidant detoxification neutrophil degranulation response to reactive oxygen species cellular response to oxidative stress protein targeting to peroxisome sources amigo quickgo orthologs databases ncbi entry oma entry species human mouse entrez 847 12359 ensembl ensg00000121691 ensmusg00000027187 uniprot p04040 p24270 refseq mrna nm_001752 nm_009804 refseq protein np_001743 np_033934 location ucsc chr 11 34 44 34 47 mb chr 2 103 28 103 32 mb pubmed search 3 4 wikidata view edit human view edit mouse catalase is a common enzyme found in nearly all living organisms exposed to oxygen such as bacteria plants and animals which catalyzes the decomposition of hydrogen peroxide to water and oxygen 5 it is a very important enzyme in protecting the cell from oxidative damage by reactive oxygen species ros catalase has one of the highest turnover numbers of all enzymes one catalase molecule can convert millions of hydrogen peroxide molecules to water and oxygen each second 6 catalase is a tetramer of four polypeptide chains each over 500 amino acids long 7 it contains four iron containing heme groups that allow the enzyme to react with hydrogen peroxide the optimum ph for human catalase is approximately 7 8 and has a fairly broad maximum the rate of reaction does not change appreciably between ph 6 8 and 7 5 9 the ph optimum for other catalases varies between 4 and 11 depending on the species 10 the optimum temperature also varies by species 11 structure edit human catalase forms a tetramer composed of four subunits each of which can be conceptually divided into four domains 12 the extensive core of each subunit is generated by an eight stranded antiparallel β barrel β1 8 with nearest neighbor connectivity capped by β barrel loops on one side and α9 loops on the other 12 a helical domain at one face of the β barrel is composed of four c terminal helices α16 α17 α18 and α19 and four helices derived from residues between β4 and β5 α4 α5 α6 and α7 12 alternative splicing may result in different protein variants history edit catalase was first noticed in 1818 by louis jacques thénard who discovered hydrogen peroxide h 2 o 2 thénard suggested its breakdown was caused by an unknown substance in 1900 oscar loew was the first to give it the name catalase and found it in many plants and animals 13 in 1937 catalase from beef liver was crystallized by james b sumner and alexander dounce 14 and the molecular weight was measured in 1938 15 the amino acid sequence of bovine catalase was determined in 1969 16 and the three dimensional structure in 1981 17 function edit molecular mechanism edit while the complete mechanism of catalase is not currently known 18 the reaction is believed to occur in two stages h 2 o 2 fe iii e h 2 o o fe iv e h 2 o 2 o fe iv e h 2 o fe iii e o 2 18 here fe e represents the iron center of the heme group attached to the enzyme fe iv e is a mesomeric form of fe v e meaning the iron is not completely oxidized to v but receives some stabilising electron density from the heme ligand which is then shown as a radical cation as hydrogen peroxide enters the active site it does interact with the amino acids asn148 asparagine at position 148 and his75 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 18 the reactivity of the iron center may be improved by the presence of the phenolate ligand of tyr358 in the fifth coordination position 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 his75 and asn148 with reaction intermediates 18 the decomposition of hydrogen peroxide by catalase proceeds according to first order kinetics the rate being proportional to the hydrogen peroxide concentration 19 catalase can also catalyze the oxidation by hydrogen peroxide of various metabolites and toxins including formaldehyde formic acid phenols acetaldehyde and alcohols it does so according to the following reaction h 2 o 2 h 2 r 2h 2 o r the exact mechanism of this reaction is not known any heavy metal ion such as copper cations in copper ii sulfate can act as a noncompetitive inhibitor of catalase however copper deficiency can lead to a reduction in catalase activity in tissues such as heart and liver 20 furthermore the poison cyanide is a noncompetitive inhibitor 21 of catalase at high concentrations of hydrogen peroxide 22 arsenate acts as an activator 23 three dimensional protein structures of the peroxidated catalase intermediates are available at the protein data bank cellular role edit hydrogen peroxide is a harmful byproduct of many normal metabolic processes to prevent damage to cells and tissues it must be quickly converted into other less dangerous substances to this end catalase is frequently used by cells to rapidly catalyze the decomposition of hydrogen peroxide into less reactive gaseous oxygen and water molecules 24 mice genetically engineered to lack catalase are initially phenotypically normal 25 however catalase deficiency in mice may increase the likelihood of developing obesity fatty liver 26 and type 2 diabetes 27 some humans have very low levels of catalase acatalasia yet show few ill effects the increased oxidative stress that occurs with aging in mice is alleviated by over expression of catalase 28 over expressing mice do not exhibit the age associated loss of spermatozoa testicular germ and sertoli cells seen in wild type mice oxidative stress in wild type mice ordinarily induces oxidative dna damage measured as 8 oxodg in sperm with aging but these damages are significantly reduced in aged catalase over expressing mice 28 furthermore these over expressing mice show no decrease in age dependent number of pups per litter overexpression of catalase targeted to mitochondria extends the lifespan of mice 29 in eukaryotes catalase is usually located in a cellular organelle called the peroxisome 30 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 2 to reactive nitrogen atoms hydrogen peroxide is used as a potent antimicrobial agent when cells are infected with a pathogen catalase positive pathogens such as mycobacterium tuberculosis legionella pneumophila and campylobacter jejuni make catalase to deactivate the peroxide radicals thus allowing them to survive unharmed within the host 31 like alcohol dehydrogenase catalase converts ethanol to acetaldehyde and drop out studies in rodents suggest that it may be responsible for the majority of this reaction in the brain 32 33 distribution among organisms edit the large majority of known organisms use catalase in every organ with particularly high concentrations occurring in the liver in mammals 34 catalase is found primarily in peroxisomes and the cytosol of erythrocytes and sometimes in mitochondria 35 almost all aerobic microorganisms use catalase it is also present in some anaerobic microorganisms such as methanosarcina barkeri 36 catalase is also universal among plants and occurs in most fungi 37 one unique use of catalase occurs in the bombardier beetle this beetle has two sets of liquids that are stored separately in two paired glands the larger of the pair the storage chamber or reservoir contains hydroquinones and hydrogen peroxide while the smaller the reaction chamber contains catalases and peroxidases to activate the noxious 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 38 the oxidation reaction is very exothermic δh 202 8 kj mol and rapidly heats the mixture to the boiling point 39 long lived queens of the termite reticulitermes speratus have significantly lower oxidative damage to their dna than non reproductive individuals workers and soldiers 40 queens have more than two times higher catalase activity and seven times higher expression levels of the catalase gene rscat1 than workers 40 it appears that the efficient antioxidant capability of termite queens can partly explain how they attain longer life catalase enzymes from various species have vastly differing optimum temperatures poikilothermic animals typically have catalases with optimum temperatures in the range of 15 25 c 59 77 f while mammalian or avian catalases might have optimum temperatures above 35 c 95 f 41 42 and catalases from plants vary depending on their growth habit 41 in contrast catalase isolated from the hyperthermophile archaeon pyrobaculum calidifontis has a temperature optimum of 90 c 194 f 43 clinical significance and application edit hydrogen peroxide catalase is used in the food industry for removing hydrogen peroxide from milk prior to cheese production 44 another use is in food wrappers where it prevents food from oxidizing 45 catalase is also used in the textile industry removing hydrogen peroxide from fabrics to make sure the material is peroxide free 46 a minor use is in contact lens hygiene a few lens cleaning products 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 47 bacterial identification catalase test edit positive catalase reaction the catalase test is one of the three main tests used by microbiologists to identify species of bacteria if the bacteria possess catalase i e are catalase positive bubbles of oxygen are observed when a small amount of bacterial isolate is added to hydrogen peroxide the catalase test is done by placing a drop of hydrogen peroxide on a microscope slide an applicator stick is touched to the colony and the tip is then smeared onto the hydrogen peroxide drop citation needed if the mixture produces bubbles or froth the organism is said to be catalase positive staphylococci 48 and micrococci 49 are catalase positive other catalase positive organisms include listeria corynebacterium diphtheriae burkholderia cepacia nocardia the family enterobacteriaceae citrobacter e coli enterobacter klebsiella shigella yersinia proteus salmonella serratia pseudomonas mycobacterium tuberculosis aspergillus cryptococcus and rhodococcus equi if not the organism is catalase negative streptococcus 50 and enterococcus spp are catalase negative while the catalase test alone cannot identify a particular organism it can aid identification when combined with other tests such as antibiotic resistance the presence of catalase in bacterial cells depends on both the growth condition and the medium used to grow the cells citation needed capillary tubes may also be used a small sample of bacteria is collected on the end of the capillary tube without blocking the tube to avoid false negative results the opposite end is then dipped into hydrogen peroxide which is drawn into the tube through capillary action and turned upside down so that the bacterial sample points downwards the hand holding the tube is then tapped on the bench moving the hydrogen peroxide down until it touches the bacteria if bubbles form on contact this indicates a positive catalase result this test can detect catalase positive bacteria at concentrations above about 10 5 cells ml 51 and is simple to use bacterial virulence edit neutrophils and other phagocytes use peroxide to kill bacteria the enzyme nadph oxidase generates superoxide within the phagosome which is converted via hydrogen peroxide to other oxidising substances like hypochlorous acid which kill phagocytosed pathogens 52 in individuals with chronic granulomatous disease cgd phagocytic peroxide production is impaired due to a defective nadph oxidase system normal cellular metabolism will still produce a small amount of peroxide and this peroxide can be used to produce hypochlorous acid to eradicate the bacterial infection however if individuals with cgd are infected with catalase positive bacteria the bacterial catalase can destroy the excess peroxide before it can be used to produce other oxidising substances in these individuals the pathogen survives and becomes a chronic infection this chronic infection is typically surrounded by macrophages in an attempt to isolate the infection this wall of macrophages surrounding a pathogen is called a granuloma many bacteria are catalase positive but some are better catalase producers than others some catalase positive bacteria and fungi include nocardia pseudomonas listeria aspergillus candida e coli staphylococcus serratia b cepacia and h pylori 53 acatalasia edit acatalasia is a condition caused by homozygous mutations in cat resulting in a lack of ...
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