Editing Amylase

{{short description|Class of enzymes}}
{{infobox enzyme
| Name = Alpha-amylase
| EC_number = 3.2.1.1
| CAS_number = 9000-90-2
| GO_code = GO:0004556
| image = Salivary alpha-amylase 1SMD.png
| width = 
| caption = Human salivary amylase: [[calcium]] [[ion]] visible in pale khaki, [[chloride]] ion in green. PDB {{PDBe|1SMD}}<ref>{{cite journal | vauthors = Ramasubbu N, Paloth V, Luo Y, Brayer GD, Levine MJ | title = Structure of human salivary alpha-amylase at 1.6&nbsp;Å resolution: implications for its role in the oral cavity | journal = Acta Crystallographica D | volume = 52 | issue = 3 | pages = 435–446 | date = May 1996 | pmid = 15299664 | doi = 10.1107/S0907444995014119 | doi-access = free }}</ref>
}}
{{infobox enzyme
| Name = Beta-amylase
| EC_number = 3.2.1.2
| CAS_number = 9000-91-3
| GO_code = GO:0016161
| image = 2xfr b amylase.png
| width = 
| caption = Structure of [[barley]] beta-amylase. PDB {{PDBe|2xfr}}<ref>{{cite journal | vauthors = Rejzek M, Stevenson CE, Southard AM, Stanley D, Denyer K, Smith AM, Naldrett MJ, Lawson DM, Field RA | s2cid = 45819617 | title = Chemical genetics and cereal starch metabolism: structural basis of the non-covalent and covalent inhibition of barley β-amylase | journal = Molecular BioSystems | volume = 7 | issue = 3 | pages = 718–730 | date = March 2011 | pmid = 21085740 | doi = 10.1039/c0mb00204f }}</ref>
}}
{{infobox enzyme
| Name = Gamma-amylase. Glucan 1,4-alpha-glucosidase
| EC_number = 3.2.1.3
| CAS_number = 9032-08-0
| GO_code = GO:0004339
| image = 
| width = 
| caption =
}}

An '''amylase''' ({{IPAc-en|ˈ|æ|m|ᵻ|l|eɪ|s}}) is an [[enzyme]] that [[catalysis|catalyses]] the [[hydrolysis]] of [[starch]] (Latin ''{{Linktext|amylum}}'') into [[sugar]]s. Amylase is present in the [[saliva]] of humans and some other mammals, where it begins the chemical process of [[digestion]]. Foods that contain large amounts of starch but little sugar, such as [[rice]] and [[potatoes]], may acquire a slightly sweet taste as they are chewed because amylase degrades some of their starch into sugar. The [[pancreas]] and salivary gland make amylase ([[alpha amylase]]) to hydrolyse dietary starch into [[disaccharides]] and [[trisaccharides]] which are converted by other enzymes to [[glucose]] to supply the body with energy. Plants and some bacteria also produce amylase. Specific amylase [[protein]]s are designated by different Greek letters. All amylases are [[glycoside hydrolase]]s and act on α-1,4-[[glycosidic bond]]s.

==Classification==

{| class="wikitable"
|-
! 
! α-amylase
! β-amylase
! γ-amylase
|-
! Source
| Animals, plants, microbes
| Plants, microbes
| Animals, microbes
|-
! Tissue
| Salivary gland, pancreas
| Seeds, fruits
| Small intestine
|-
! Cleavage site
| Random α-1,4 glycosidic bond
| Second α-1,4 glycosidic bond
| Last α-1,4 glycosidic bond
|-
! Reaction products
| [[Maltose]], [[dextrin]], etc.
| Maltose
| [[Glucose]]
|-
! Optimum pH
| 6.7–7.0
| 5.4–5.5
| 4.0–4.5
|-
! Optimum temperature in brewing
| {{convert|68|–|74|C|F}}
| {{convert|58|–|65|C|F}}
| {{convert|63|–|68|C|F}}
|}

===α-Amylase===
{{main|Alpha-amylase}}
The α-amylases ({{EC number|3.2.1.1 }}) ([[CAS registry number|CAS]] 9014–71–5) (alternative names: 1,4-α-<small>D</small>-glucan glucanohydrolase; glycogenase) are [[calcium]] [[metalloprotein|metalloenzymes]]. By acting at random locations along the starch chain, α-amylase breaks down long-chain [[saccharides]], ultimately yielding either [[maltotriose]] and [[maltose]] from [[amylose]], or maltose, [[glucose]] and [[dextrin|"limit dextrin"]] from [[amylopectin]]. They belong to [[glycoside hydrolase family 13]] (https://www.cazypedia.org/index.php/Glycoside_Hydrolase_Family_13).

Because it can act anywhere on the [[Substrate (biochemistry)|substrate]], α-amylase tends to be faster-acting than β-amylase. In [[animal]]s, it is a major [[digestion|digestive]] enzyme, and its optimum pH is 6.7–7.0.<ref>{{cite web|url=http://www.worthington-biochem.com/introbiochem/effectspH.html|title=Effects of pH (Introduction to Enzymes)|website=worthington-biochem.com|access-date=17 May 2015}}</ref>

In human physiology, both the salivary and pancreatic amylases are α-amylases.

The α-amylase form is also found in plants, fungi ([[ascomycetes]] and [[basidiomycetes]]) and bacteria (''[[Bacillus]]'').

===β-Amylase===
{{main|Beta-Amylase}}
Another form of amylase, β-amylase ({{EC number|3.2.1.2 }}) (alternative names: 1,4-α-<small>D</small>-glucan maltohydrolase; glycogenase; saccharogen amylase) is also synthesized by [[bacteria]], [[fungi]], and [[plant]]s. Working from the non-reducing end, β-amylase catalyzes the hydrolysis of the second α-1,4 glycosidic bond, cleaving off two glucose units ([[maltose]]) at a time. During the [[ripening]] of [[fruit]], β-amylase breaks starch into maltose, resulting in the sweet flavor of ripe fruit. They belong to [[glycoside hydrolase family 14]].

Both α-amylase and β-amylase are present in seeds; β-amylase is present in an inactive form prior to [[germination]], whereas α-amylase and proteases appear once germination has begun. Many [[microbe]]s also produce amylase to degrade extracellular starches.  [[Animal]] tissues do not contain β-amylase, although it may be present in microorganisms contained within the [[Gastrointestinal tract|digestive tract]]. The optimum pH for β-amylase is 4.0–5.0.<ref name="worthington-biochem.com">{{cite web|url=http://www.worthington-biochem.com/BA/default.html |title=Amylase, Alpha, I.U.B.: 3.2.1.11,4-α-D-Glucan glucanohydrolase}}</ref>

===γ-Amylase{{anchor|Flatulence}}===
<!-- This section is linked from [[Flatulence]] -->
{{main|Glucan 1,4-a-glucosidase}}
γ-Amylase ({{EC number|3.2.1.3 }}) (alternative names: Glucan 1,4-a-glucosidase; amyloglucosidase; ''exo''-1,4-α-glucosidase; glucoamylase; lysosomal α-glucosidase; 1,4-α-<small>D</small>-glucan glucohydrolase) will cleave α(1–6) glycosidic linkages, as well as the last α-1,4 glycosidic bond at the nonreducing end of [[amylose]] and [[amylopectin]], yielding [[glucose]]. The γ-amylase has the most acidic optimum pH of all amylases because it is most active around pH 3. They belong to a variety of different [[glycoside hydrolase]] families, such as [[glycoside hydrolase family 15]] in fungi, [[glycoside hydrolase family 31]] of human [[Maltase-glucoamylase|MGAM]], and [[glycoside hydrolase family 97]] of bacterial forms.

==Uses==

===Fermentation===
α- and β-amylases are important in [[brewing]] beer and liquor made from sugars derived from [[starch]]. In [[fermentation]], [[yeast]] ingests sugars and excretes [[ethanol]]. In beer and some liquors, the sugars present at the beginning of fermentation have been produced by "mashing" grains or other starch sources (such as [[potato]]es). In traditional beer brewing, [[malted barley]] is mixed with hot water to create a "[[Mash (beer)|mash]]", which is held at a given temperature to allow the amylases in the malted grain to convert the barley's starch into sugars. Different temperatures optimize the activity of alpha or beta amylase, resulting in different mixtures of fermentable and unfermentable sugars. In selecting mash temperature and grain-to-water ratio, a brewer can change the alcohol content, [[mouthfeel]], aroma, and flavor of the finished beer.

In some historic methods of producing alcoholic beverages, the conversion of starch to sugar starts with the brewer chewing grain to mix it with saliva.<ref>{{cite news |title=Chew It Up, Spit It Out, Then Brew. Cheers! |url=https://www.nytimes.com/2009/09/09/dining/09beer.html?pagewanted=all&_r=0 |work=New York Times | date=8 September 2009 |access-date=27 March 2013| vauthors = Wadler J }}</ref> This practice continues to be practiced in home production of some traditional drinks, such as [[chhaang]] in the Himalayas, [[chicha]]  in the Andes and [[kasiri]] in [[Brazil]] and [[Suriname]].

===Flour additive===
Amylases are used in [[breadmaking]] and to break down complex sugars, such as starch (found in [[flour]]), into simple sugars. [[Yeast]] then feeds on these simple sugars and converts it into the waste products of [[ethanol]] and [[carbon dioxide]]. This imparts flavour and causes the bread to rise. While amylases are found naturally in yeast cells, it takes time for the yeast to produce enough of these enzymes to break down significant quantities of starch in the bread. This is the reason for long fermented doughs such as [[sourdough]]. Modern breadmaking techniques have included amylases (often in the form of [[malted barley]]) into [[bread improver]], thereby making the process faster and more practical for commercial use.<ref>{{cite book | vauthors = Maton A, Hopkins J, McLaughlin CW, Johnson S, Warner MQ, LaHart D, Wright JD | title = Human Biology and Health | publisher = Prentice Hall | year = 1993 | location = Englewood Cliffs, NJ | isbn = 0-13-981176-1 | url-access = registration | url = https://archive.org/details/humanbiologyheal00scho }}</ref>{{failed verification|date=February 2019}}

α-Amylase is often listed as an ingredient on commercially package-milled flour. Bakers with long exposure to amylase-enriched flour are at risk of developing [[dermatitis]]<ref>{{cite journal | vauthors = Morren MA, Janssens V, Dooms-Gossens A, Van Hoeyveld E, Cornelis A, De Wolf-Peeters C, Heremans A | title = alpha-Amylase, a flour additive: an important cause of protein contact dermatitis in bakers | journal = Journal of the American Academy of Dermatology | volume = 29 | issue = 5 Pt 1 | pages = 723–728 | date = November 1993 | pmid = 8227545 | doi = 10.1016/0190-9622(93)70237-n }}</ref> or [[asthma]].<ref>{{cite journal | vauthors = Park HS, Kim HY, Suh YJ, Lee SJ, Lee SK, Kim SS, Nahm DH | title = Alpha amylase is a major allergenic component in occupational asthma patients caused by porcine pancreatic extract | journal = The Journal of Asthma | volume = 39 | issue = 6 | pages = 511–516 | date = September 2002 | pmid = 12375710 | doi = 10.1081/jas-120004918 | s2cid = 23522631 }}</ref>

===Molecular biology===
In [[molecular biology]], the presence of amylase can serve as an additional method of selecting for successful integration of a reporter construct in addition to [[antibiotic resistance]]. As reporter genes are flanked by homologous regions of the structural gene for amylase, successful integration will disrupt the amylase gene and prevent starch degradation, which is easily detectable through [[Iodine test|iodine staining]].

===Medical uses===
Amylase also has medical applications in the use of [[pancreatic enzyme replacement therapy]] (PERT). It is one of the components in Sollpura ([[liprotamase]]) to help in the breakdown of [[saccharides]] into simple sugars.<ref>{{cite web|title=Sollpura|publisher=Anthera Pharmaceuticals|access-date=21 July 2015|url=http://www.anthera.com/pipeline/science/sollpura.html|archive-url=https://web.archive.org/web/20150718042137/http://www.anthera.com/pipeline/science/sollpura.html|archive-date=18 July 2015}}</ref>

===Other uses===
An inhibitor of alpha-amylase, called [[phaseolamin]], has been tested as a potential [[Diet (nutrition)|diet]] aid.<ref>{{cite journal | vauthors = Udani J, Hardy M, Madsen DC | title = Blocking saccharide absorption and weight loss: a clinical trial using Phase 2 brand proprietary fractionated white bean extract | journal = Alternative Medicine Review | volume = 9 | issue = 1 | pages = 63–69 | date = March 2004 | pmid = 15005645 | url = http://www.thorne.com/altmedrev/.fulltext/9/1/63.pdf | archive-url = https://web.archive.org/web/20110728045340/http://www.thorne.com/altmedrev/.fulltext/9/1/63.pdf | url-status = dead | archive-date = 2011-07-28 }}</ref>

When used as a [[food additive]], amylase has [[E number]] E1100, and may be derived from [[pig]] pancreas or [[Mold (fungus)|mold]] fungi.

Bacilliary amylase is also used in clothing and dishwasher [[detergent]]s to dissolve starches from fabrics and dishes.

Factory workers who work with amylase for any of the above uses are at increased risk of [[occupational asthma]]. Five to nine percent of bakers have a positive skin test, and a fourth to a third of bakers with breathing problems are hypersensitive to amylase.<ref>{{cite journal | vauthors = Mapp CE | title = Agents, old and new, causing occupational asthma | journal = Occupational and Environmental Medicine | volume = 58 | issue = 5 | pages = 354–360, 290 | date = May 2001 | pmid = 11303086 | pmc = 1740131 | doi = 10.1136/oem.58.5.354 }}</ref>

==Hyperamylasemia==
[[Blood serum]] amylase may be measured for purposes of [[medical diagnosis]]. A higher than normal concentration may reflect any of several medical conditions, including [[acute (medicine)|acute]] [[inflammation]] of the [[acute pancreatitis|pancreas]] (which may be measured concurrently with the more specific [[lipase]]),<ref>{{cite web|url=http://www.merck.com/mmpe/print/sec02/ch015=/ch015b.html|title=Acute Pancreatitis – Gastrointestinal Disorders|website=Merck Manuals Professional Edition|publisher=Merck}}{{Dead link|date=February 2022 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> perforated [[peptic ulcer]], torsion of an [[ovarian cyst]], [[strangulation]], [[ileus]], [[mesenteric ischemia]], [[macroamylasemia]] and [[mumps]]. Amylase may be measured in other body fluids, including [[urine]] and [[peritoneum|peritoneal]] fluid.

A January 2007 study from [[Washington University in St. Louis]] suggests that saliva tests of the enzyme could be used to indicate [[sleep deficit]]s, as the enzyme increases its activity in correlation with the length of time a subject has been deprived of sleep.<ref>{{cite web|url=http://record.wustl.edu/news/page/normal/8539.html|title=First Biomarker for Human Sleepiness Identified|website=Record|publisher=[[Washington University in St. Louis]]|date=25 January 2007|access-date=7 July 2013|archive-date=7 October 2007|archive-url=https://web.archive.org/web/20071007071836/http://record.wustl.edu/news/page/normal/8539.html|url-status=dead}}</ref>

==History==
In 1831, [[Erhard Friedrich Leuchs]] (1800–1837) described the [[hydrolysis]] of starch by saliva, due to the presence of an enzyme in saliva, "[[ptyalin]]", an amylase.<ref>
*{{cite journal|vauthors=Leuchs EF |date=1831 |url=https://books.google.com/books?id=KSEAAAAAMAAJ&pg=PA623 |title=Wirkung des Speichels auf Stärke |trans-title=Effect of saliva on starch |journal=Poggendorff's Annalen der Physik und Chemie|volume=22|issue=8 |page=623|doi=10.1002/andp.18310980814 |bibcode=1831AnP....98..623L }} (Modern citation: ''Annalen der Physik'' '''98''' (8): 623.)
*{{cite journal|vauthors=Leuchs EF|date=1831|url=https://books.google.com/books?id=hecOAAAAYAAJ&pg=PA105|title=Über die Verzuckerung des Stärkmehls durch Speichel|trans-title=On the saccharification of powdered starch by saliva|journal=Archiv für die gesammte Naturlehre|volume=21|pages=105–107}}</ref><ref>{{cite web|url=http://www.pasteur.fr/recherche/unites/REG/causeries/dates_1800.html|title=History of Biology: Cuvier, Schwann and Schleiden|date=8 April 2002|work=pasteur.fr|access-date=17 May 2015|archive-url=https://web.archive.org/web/20150924090421/http://www.pasteur.fr/recherche/unites/REG/causeries/dates_1800.html|archive-date=24 September 2015|url-status=dead|df=dmy-all}}</ref> it was named after the Ancient Greek name for saliva: {{lang|grc|πτύαλον}} - {{lang|grc-Latn|ptyalon}}.

The modern history of enzymes began in 1833, when French chemists [[Anselme Payen]] and [[Jean-François Persoz]] isolated an amylase complex from germinating barley and named it "[[diastase]]".<ref>{{cite journal | title = Mémoire sur la diastase, les principaux produits de ses réactions et leurs applications aux arts industriels |trans-title = Memoir on diastase, the principal products of its reactions and their applications to the industrial arts | year = 1833 | journal = Annales de chimie et de physique | series = 2nd series | vauthors = Payen A, Persoz JF | volume = 53 | pages = 73–92 | url = https://books.google.com/books?id=Q9I3AAAAMAAJ&pg=PA73 }}</ref><ref>{{cite web|url=http://www.anbio.org.br/english/worksh52.htm  |title=Industrial Enzymes for Food Production |archive-url=https://web.archive.org/web/20081205092157/http://www.anbio.org.br/english/worksh52.htm |archive-date=5 December 2008 }}</ref> It is from this term that all subsequent enzyme names tend to end in the suffix -ase.

In 1862, Russian biochemist {{ill|Aleksandr Danilevsky|lt=Aleksandr Yakovlevich Danilevsky|ru|Данилевский, Александр Яковлевич}} (1838–1923) separated pancreatic amylase from [[trypsin]].<ref>{{cite journal|vauthors=Danilewsky AJ |date=1862 |url=https://books.google.com/books?id=cIIvAAAAIAAJ |title=Über specifisch wirkende Körper des natürlichen und künstlichen pancreatischen Saftes |trans-title=On the specifically-acting principles of natural and artificial pancreatic fluid |journal=Virchows Archiv für Pathologische Anatomie und Physiologie und für Klinische Medizin |volume=25 |pages=279–307}} [https://books.google.com/books?id=MVEBAAAAYAAJ&dq=danilewsky&pg=PA226 Abstract (in English).]</ref><ref>{{cite web|url=http://www.navi.net/~rsc/cancer/enzymhis.txt|title=A History of Fermentation and Enzymes|website=navi.net|access-date=2008-10-25|archive-date=2022-01-10|archive-url=https://web.archive.org/web/20220110072036/http://www.navi.net/~rsc/cancer/enzymhis.txt|url-status=dead}}</ref>

==Evolution{{anchor|human evolution}}==

=== Salivary amylase ===
{{See also|Alpha-amylase#Salivary amylase (ptyalin)}}
[[Saccharides]] are a food source rich in energy. Large polymers such as starch are partially hydrolyzed in the mouth by the enzyme amylase before being cleaved further into sugars. Many mammals have seen great expansions in the copy number of the amylase gene. These duplications allow for the pancreatic amylase ''AMY2'' to re-target to the salivary glands, allowing animals to detect starch by taste and to digest starch more efficiently and in higher quantities. This has happened independently in mice, rats, dogs, pigs, and most importantly, humans after the agricultural revolution.<ref name=Pajic2019>{{cite journal | vauthors = Pajic P, Pavlidis P, Dean K, Neznanova L, Romano RA, Garneau D, Daugherity E, Globig A, Ruhl S, Gokcumen O | display-authors = 6 | title = Independent amylase gene copy number bursts correlate with dietary preferences in mammals | journal = eLife | volume = 8 | date = May 2019 | pmid = 31084707 | pmc = 6516957 | doi = 10.7554/eLife.44628 | doi-access = free }}</ref>

Following the [[First agricultural revolution|agricultural revolution]] 12,000 years ago, human diet began to shift more to plant and animal [[domestication]] in place of [[Hunter-gatherer|hunting and gathering]]. Starch has become a staple of the human diet.

Despite the obvious benefits, early humans did not possess salivary amylase, a trend that is also seen in evolutionary relatives of the human, such as [[chimpanzee]]s and [[bonobo]]s, who possess either one or no copies of the gene responsible for producing salivary amylase.<ref>{{cite journal| vauthors = Vuorisalo T, Arjamaa O |title=Gene-Culture Coevolution and Human Diet |journal=American Scientist |date=March–April 2010 |volume=98 |issue=2 |page=140 |url=http://www.americanscientist.org/issues/feature/2010/2/gene-culture-coevolution-and-human-diet |doi=10.1511/2010.83.140|access-date=2015-08-15|archive-date=2016-03-04|archive-url=https://web.archive.org/web/20160304110626/http://www.americanscientist.org/issues/feature/2010/2/gene-culture-coevolution-and-human-diet|url-status=dead}}</ref>

Like in other mammals, the pancreatic alpha-amylase ''AMY2'' was duplicated multiple times. One event allowed it to evolve salivary specificity, leading to the production of amylase in the saliva (named in humans as ''AMY1''). The 1p21.1 region of human chromosome 1 contains many copies of these genes, variously named ''[[AMY1A]]'', ''[[AMY1B]]'', ''[[AMY1C]]'', ''[[AMY2A]]'', ''[[AMY2B]]'', and so on.<ref name=Perry2007>{{cite journal | vauthors = Perry GH, Dominy NJ, Claw KG, Lee AS, Fiegler H, Redon R, Werner J, Villanea FA, Mountain JL, Misra R, Carter NP, Lee C, Stone AC | title = Diet and the evolution of human amylase gene copy number variation | journal = Nature Genetics | volume = 39 | issue = 10 | pages = 1256–1260 | date = October 2007 | pmid = 17828263 | pmc = 2377015 | doi = 10.1038/ng2123 }}</ref>

However, not all humans possess the same number of copies of the ''AMY1'' gene. Populations known to rely more on saccharides have a higher number of AMY1 copies than human populations that, by comparison, consume little starch. The number of ''AMY1'' gene copies in humans can range from six copies in agricultural groups such as European-American and Japanese (two high starch populations) to only two to three copies in hunter-gatherer societies such as the [[Aka people|Biaka]], [[Datog]], and [[Yakuts]].<ref name=Perry2007/>

The correlation that exists between starch consumption and number of ''AMY1'' copies specific to population suggest that more AMY1 copies in high starch populations has been selected for by natural selection and considered the favorable phenotype for those individuals. Therefore, it is most likely that the benefit of an individual possessing more copies of ''AMY1'' in a high starch population increases fitness and produces healthier, fitter offspring.<ref name=Perry2007/>

This fact is especially apparent when comparing geographically close populations with different eating habits that possess a different number of copies of the ''AMY1'' gene. Such is the case for some Asian populations that have been shown to possess few ''AMY1'' copies relative to some agricultural populations in Asia. This offers strong evidence that natural selection has acted on this gene as opposed to the possibility that the gene has spread through genetic drift.<ref name=Perry2007/>

Variations of amylase copy number in dogs mirrors that of human populations, suggesting they acquired the extra copies as they followed humans around.<ref>{{cite journal | vauthors = Arendt M, Cairns KM, Ballard JW, Savolainen P, Axelsson E | title = Diet adaptation in dog reflects spread of prehistoric agriculture | journal = Heredity | volume = 117 | issue = 5 | pages = 301–306 | date = November 2016 | pmid = 27406651 | pmc = 5061917 | doi = 10.1038/hdy.2016.48 | doi-access = free }}</ref> Unlike humans whose amylase levels depend on starch content in diet, wild animals eating a broad range of foods tend to have more copies of amylase. This may have to do with mainly detection of starch as opposed to digestion.<ref name=Pajic2019/>

== References ==
{{reflist|30em}}

{{Clinical biochemistry blood tests}}
{{Sugar hydrolases}}
{{Enzymes}}
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[[Category:Chemical pathology]]
[[Category:EC 3.2.1]]
[[Category:Enzymes]]
[[Category:Food additives]]
[[Category:Saliva]]
[[Category:Enzymes of known structure]]