Editing Enzyme (section)

{{short description|Large biological molecule that acts as a catalyst}}
{{redirect|Biocatalyst|the use of natural catalysts in organic chemistry|Biocatalysis}}
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[[File:Glucosidase enzyme.png|thumb|400px|The enzyme [[glucosidase]] converts the sugar [[maltose]] into two [[glucose]] sugars. [[Active site]] residues in red, maltose substrate in black, and [[Nicotinamide adenine dinucleotide|NAD]] [[Cofactor (biochemistry)|cofactor]] in yellow. ({{PDB|1OBB}})|alt=Ribbon diagram of glycosidase with an arrow showing the cleavage of the maltose sugar substrate into two glucose products.]]
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An '''enzyme''' ({{IPAc-en|ˈ|ɛ|n|z|aɪ|m}}) is a [[protein]] that acts as a biological [[catalyst]] by accelerating [[chemical reactions]]. The [[molecules]] upon which enzymes may act are called [[substrate (chemistry)|substrates]], and the enzyme converts the substrates into different molecules known as [[product (chemistry)|products]]. Almost all [[metabolism|metabolic processes]] in the [[cell (biology)|cell]] need [[enzyme catalysis]] in order to occur at rates fast enough to sustain life.<ref name = "Stryer_2002">{{cite book |vauthors=Stryer L, Berg JM, Tymoczko JL | title = Biochemistry | publisher = W.H. Freeman | location = San Francisco | year = 2002 | edition = 5th | isbn = 0-7167-4955-6 | url = https://www.ncbi.nlm.nih.gov/books/NBK21154/}}{{Open access}}</ref>{{rp|8.1}} [[Metabolic pathway]]s depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of [[pseudoenzyme|pseudoenzyme analysis]] recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their [[amino acid]] sequences and unusual 'pseudocatalytic' properties.<ref>{{cite journal | vauthors = Murphy JM, Farhan H, Eyers PA | title = Bio-Zombie: the rise of pseudoenzymes in biology | journal = Biochemical Society Transactions | volume = 45 | issue = 2 | pages = 537–544 | date = April 2017 | pmid = 28408493 | doi = 10.1042/bst20160400 }}</ref><ref name="pmid24107129">{{cite journal | vauthors = Murphy JM, Zhang Q, Young SN, Reese ML, Bailey FP, Eyers PA, Ungureanu D, Hammaren H, Silvennoinen O, Varghese LN, Chen K, Tripaydonis A, Jura N, Fukuda K, Qin J, Nimchuk Z, Mudgett MB, Elowe S, Gee CL, Liu L, Daly RJ, Manning G, Babon JJ, Lucet IS | title = A robust methodology to subclassify pseudokinases based on their nucleotide-binding properties | journal = The Biochemical Journal | volume = 457 | issue = 2 | pages = 323–334 | date = January 2014 | pmid = 24107129 | pmc = 5679212 | doi = 10.1042/BJ20131174 }}</ref>

Enzymes are known to catalyze more than 5,000 biochemical reaction types.<ref>{{cite journal | vauthors = Schomburg I, Chang A, Placzek S, Söhngen C, Rother M, Lang M, Munaretto C, Ulas S, Stelzer M, Grote A, Scheer M, Schomburg D | title = BRENDA in 2013: integrated reactions, kinetic data, enzyme function data, improved disease classification: new options and contents in BRENDA | journal = Nucleic Acids Research | volume = 41 | issue = Database issue | pages = D764–D772 | date = January 2013 | pmid = 23203881 | pmc = 3531171 | doi = 10.1093/nar/gks1049 }}</ref>

Other biocatalysts include [[Ribozyme|catalytic RNA molecules]], also called [[ribozyme]]s. They are sometimes described as a ''type'' of enzyme rather than being ''like'' an enzyme, but even in the decades since ribozymes' discovery in 1980–1982, the word ''enzyme'' alone often means the protein type specifically (as is used in this article). A third category of biocatalysts is constituted by those [[biomolecular condensate]]s that have catalytic ability.<ref name=Ball-2025-01-21>{{cite journal |date=2025-01-21 |author=Philip Ball |editor=Jen Schwartz |title=Mysterious Blobs Found inside Cells Are Rewriting the Story of How Life Works. Tiny specks called biomolecular condensates are leading to a new understanding of the cell |journal=Scientific American |volume=332 |issue=2 (February) |url=https://www.scientificamerican.com/article/mysterious-blobs-found-in-cells-are-rewriting-how-life-works/ |quote=Condensates can act as catalysts for biochemical reactions, even if their component proteins do not. This is because condensates create an interface between two phases, which sets up a gradient in concentrations—of ions for example, creating an electric field that can trigger reactions. The researchers have demonstrated condensate-induced catalysis of a wide range of biochemical reactions, including those involving hydrolysis (in which water splits other molecules apart).}}</ref>

An enzyme's [[Chemical specificity|specificity]] comes from its unique [[tertiary structure|three-dimensional structure]].

[[File:IUPAC definition for enzymes.png|thumb|right|550px|link=https://doi.org/10.1351/goldbook.E02159|IUPAC definition for enzymes]]

Like all catalysts, enzymes increase the [[reaction rate]] by lowering its [[activation energy]]. Some enzymes can make their conversion of substrate to product occur many millions of times faster. An extreme example is [[orotidine 5'-phosphate decarboxylase]], which allows a reaction that would otherwise take millions of years to occur in milliseconds.<ref name="radzicka">{{cite journal | vauthors = Radzicka A, Wolfenden R | title = A proficient enzyme | journal = Science | volume = 267 | issue = 5194 | pages = 90–93 | date = January 1995 | pmid = 7809611 | doi = 10.1126/science.7809611 | s2cid = 8145198 | bibcode = 1995Sci...267...90R }}</ref><ref name="pmid17889251">{{cite journal | vauthors = Callahan BP, Miller BG | title = OMP decarboxylase--An enigma persists | journal = Bioorganic Chemistry | volume = 35 | issue = 6 | pages = 465–469 | date = December 2007 | pmid = 17889251 | doi = 10.1016/j.bioorg.2007.07.004 }}</ref> Chemically, enzymes are like any catalyst and are not consumed in chemical reactions, nor do they alter the [[Chemical equilibrium|equilibrium]] of a reaction. Enzymes differ from most other catalysts by being much more specific. Enzyme activity can be affected by other molecules: [[Enzyme inhibitor|inhibitors]] are molecules that decrease enzyme activity, and [[enzyme activator|activators]] are molecules that increase activity. Many therapeutic [[drug]]s and [[poison]]s are enzyme inhibitors. An enzyme's activity decreases markedly outside its optimal [[temperature]] and [[pH]], and many enzymes are (permanently) [[Denaturation (biochemistry)|denatured]] when exposed to excessive heat, losing their structure and catalytic properties.

Some enzymes are used commercially, for example, in the synthesis of [[antibiotic]]s. Some household products use enzymes to speed up chemical reactions: enzymes in [[Detergent enzymes|biological washing powder]]s break down protein, starch or [[fat]] stains on clothes, and enzymes in [[papain|meat tenderizer]] break down proteins into smaller molecules, making the meat easier to chew.
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