An amylase () is an
enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...
that
catalyses the
hydrolysis
Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...
of
starch
Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets ...
(Latin ') into
sugar
Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose, fructose, and galactose. Compound sugars, also called disaccharides or double ...
s. Amylase is present in the
saliva
Saliva (commonly referred to as spit) is an extracellular fluid produced and secreted by salivary glands in the mouth. In humans, saliva is around 99% water, plus electrolytes, mucus, white blood cells, epithelial cells (from which DNA can be ...
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
Rice is the seed of the grass species ''Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima
''Oryza glaberrima'', commonly known as African rice, is one of the two domesticated rice species. It was first domesticated and grown i ...
and
potatoes
The potato is a starchy food, a tuber of the plant ''Solanum tuberosum'' and is a root vegetable native to the Americas. The plant is a perennial in the nightshade family Solanaceae.
Wild potato species can be found from the southern United ...
, may acquire a slightly sweet taste as they are chewed because amylase degrades some of their starch into sugar. The
pancreas
The pancreas is an organ of the digestive system and endocrine system of vertebrates. In humans, it is located in the abdomen behind the stomach and functions as a gland. The pancreas is a mixed or heterocrine gland, i.e. it has both an end ...
and salivary gland make amylase (
alpha amylase) to hydrolyse dietary starch into
disaccharides and
trisaccharides
''Trisaccharides'' are oligosaccharides composed of three monosaccharides with two glycosidic bonds connecting them. Similar to the disaccharides, each glycosidic bond can be formed between any hydroxyl group on the component monosaccharides. Even ...
which are converted by other enzymes to
glucose
Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using ...
to supply the body with energy. Plants and some bacteria also produce amylase. Specific amylase
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
s are designated by different Greek letters. All amylases are
glycoside hydrolase
Glycoside hydrolases (also called glycosidases or glycosyl hydrolases) catalyze the hydrolysis of glycosidic bonds in complex sugars. They are extremely common enzymes with roles in nature including degradation of biomass such as cellulose (cel ...
s and act on α-1,4-
glycosidic bonds.
Classification
α-Amylase
The α-amylases () (
CAS
Cas may refer to:
* Caș, a type of cheese made in Romania
* ' (1886–) Czech magazine associated with Tomáš Garrigue Masaryk
* '' Čas'' (19 April 1945–February 1948), the official, daily newspaper of the Democratic Party of Slovakia
* ''CA ...
9014-71-5) (alternative names: 1,4-α-
D-glucan glucanohydrolase; glycogenase) are
calcium
Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to ...
metalloenzymes
Metalloprotein is a generic term for a protein that contains a metal ion cofactor. A large proportion of all proteins are part of this category. For instance, at least 1000 human proteins (out of ~20,000) contain zinc-binding protein domains al ...
. By acting at random locations along the starch chain, α-amylase breaks down long-chain
saccharides, ultimately yielding either
maltotriose and
maltose
}
Maltose ( or ), also known as maltobiose or malt sugar, is a disaccharide formed from two units of glucose joined with an α(1→4) bond. In the isomer isomaltose, the two glucose molecules are joined with an α(1→6) bond. Maltose is the two- ...
from
amylose, or maltose,
glucose
Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using ...
and
"limit dextrin" from
amylopectin. They belong to
glycoside hydrolase family 13.
Because it can act anywhere on the
substrate
Substrate may refer to:
Physical layers
*Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached
** Substrate (locomotion), the surface over which an organism lo ...
, α-amylase tends to be faster-acting than β-amylase. In
animal
Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...
s, it is a major
digestive enzyme, and its optimum pH is 6.7–7.0.
In human physiology, both the salivary and pancreatic amylases are α-amylases.
The α-amylase form is also found in plants, fungi (
ascomycetes
Ascomycota is a phylum of the kingdom Fungi that, together with the Basidiomycota, forms the subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. It is the largest phylum of Fungi, with over 64,000 species. The defi ...
and
basidiomycetes
Basidiomycota () is one of two large divisions that, together with the Ascomycota, constitute the subkingdom Dikarya (often referred to as the "higher fungi") within the kingdom Fungi. Members are known as basidiomycetes. More specifically, Basi ...
) and bacteria (''
Bacillus'').
β-Amylase
Another form of amylase, β-amylase () (alternative names: 1,4-α-
D-glucan maltohydrolase; glycogenase; saccharogen amylase) is also synthesized by
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
,
fungi
A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...
, and
plant
Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclud ...
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
}
Maltose ( or ), also known as maltobiose or malt sugar, is a disaccharide formed from two units of glucose joined with an α(1→4) bond. In the isomer isomaltose, the two glucose molecules are joined with an α(1→6) bond. Maltose is the two- ...
) at a time. During the
ripening of
fruit
In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering.
Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...
, 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
Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, fer ...
, whereas α-amylase and proteases appear once germination has begun. Many
microbe
A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...
s also produce amylase to degrade extracellular starches.
Animal
Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...
tissues do not contain β-amylase, although it may be present in microorganisms contained within the
digestive tract. The optimum pH for β-amylase is 4.0–5.0.
γ-Amylase
γ-Amylase () (alternative names: Glucan 1,4-a-glucosidase; amyloglucosidase; ''exo''-1,4-α-glucosidase; glucoamylase; lysosomal α-glucosidase; 1,4-α-
D-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
Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using ...
. 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 GH families, such as
glycoside hydrolase family 15
In molecular biology, glycoside hydrolase family 15 is a family of glycoside hydrolases.
Glycoside hydrolases are a widespread group of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a ...
in fungi,
glycoside hydrolase family 31
In molecular biology, glycoside hydrolase family 31 is a family of glycoside hydrolases.
Glycoside hydrolases are a widespread group of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a ...
of human
MGAM
Maltase-glucoamylase, intestinal is an enzyme that in humans is encoded by the ''MGAM'' gene.
Maltase-glucoamylase is an alpha-glucosidase digestive enzyme. It consists of two subunits with differing substrate specificity. Recombinant enzyme stu ...
, and
glycoside hydrolase family 97
In molecular biology, glycoside hydrolase family 97 is a family of glycoside hydrolases.
Glycoside hydrolases are a widespread group of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a ...
of bacterial forms.
Uses
Fermentation
α- and β-amylases are important in
brewing
Brewing is the production of beer by steeping a starch source (commonly cereal grains, the most popular of which is barley) in water and #Fermenting, fermenting the resulting sweet liquid with Yeast#Beer, yeast. It may be done in a brewery ...
beer and liquor made from sugars derived from
starch
Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets ...
. In
fermentation
Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food ...
,
yeast
Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitut ...
ingests sugars and excretes
ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an Alcohol (chemistry), alcohol with the chemical formula . Its formula can be also written as or (an ethyl ...
. 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
The potato is a starchy food, a tuber of the plant ''Solanum tuberosum'' and is a root vegetable native to the Americas. The plant is a perennial in the nightshade family Solanaceae.
Wild potato species can be found from the southern Unit ...
es). In traditional beer brewing,
malted barley is mixed with hot water to create a "
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
Mouthfeel refers to the physical sensations in the mouth caused by food or drink, making it distinct from taste. It is a fundamental sensory attribute which, along with taste and smell, determines the overall flavor of a food item. Mouthfeel is ...
, 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. This practice continues to be practiced in home production of some traditional drinks, such as
chhaang
Chhaang or chhyang (, ne, छ्याङ, new, थो:) is a Nepalese and Tibetan alcoholic beverage also popular in parts of the eastern Himalayas, Yakkha, Limbu, Dura, Newar, Sunuwar, Rai, Gurung, Magar, Sherpa, Tamang and Lepcha comm ...
in the Himalayas,
chicha
''Chicha'' is a fermented (alcoholic) or non-fermented beverage of Latin America, emerging from the Andes and Amazonia regions. In both the pre- and post-Spanish conquest periods, corn beer (''chicha de jora'') made from a variety of maize land ...
in the Andes and
kasiri
Kasiri, also known as kaschiri and cassava beer, is an alcoholic drink made from cassava by Amerindians in Suriname and Guyana.
The roots of the cassava plant are grated, diluted in water, and pressed in a cylindrical basketwork press to extract t ...
in
Brazil
Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
and
Suriname
Suriname (; srn, Sranankondre or ), officially the Republic of Suriname ( nl, Republiek Suriname , srn, Ripolik fu Sranan), is a country on the northeastern Atlantic coast of South America. It is bordered by the Atlantic Ocean to the north ...
.
Flour additive
Amylases are used in
breadmaking
Bread is a staple food prepared from a dough of flour (usually wheat) and water, usually by baking. Throughout recorded history and around the world, it has been an important part of many cultures' diet. It is one of the oldest human-made food ...
and to break down complex sugars, such as starch (found in
flour
Flour is a powder made by grinding raw grains, roots, beans, nuts, or seeds. Flours are used to make many different foods. Cereal flour, particularly wheat flour, is the main ingredient of bread, which is a staple food for many culture ...
), into simple sugars.
Yeast
Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitut ...
then feeds on these simple sugars and converts it into the waste products of
ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an Alcohol (chemistry), alcohol with the chemical formula . Its formula can be also written as or (an ethyl ...
and
carbon dioxide
Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...
. 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
Sourdough or sourdough bread is a bread made by the fermentation of dough using wild lactobacillaceae and yeast. Lactic acid from fermentation imparts a sour taste and improves keeping qualities.
History
In the ''Encyclopedia of Food Microbio ...
. Modern breadmaking techniques have included amylases (often in the form of
malted barley) into
bread improver
A dough conditioner, flour treatment agent, improving agent or bread improver is any ingredient or chemical added to bread dough to strengthen its texture or otherwise improve it in some way. Dough conditioners may include enzymes, yeast nutrient ...
, thereby making the process faster and more practical for commercial use.
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
Dermatitis is inflammation of the skin, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened. The area of skin involved can v ...
or
asthma
Asthma is a long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wheezing, cou ...
.
Molecular biology
In
molecular biology
Molecular biology is the branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions. The study of chemical and physi ...
, the presence of amylase can serve as an additional method of selecting for successful integration of a reporter construct in addition to
antibiotic resistance
Antimicrobial resistance (AMR) occurs when microbes evolve mechanisms that protect them from the effects of antimicrobials. All classes of microbes can evolve resistance. Fungi evolve antifungal resistance. Viruses evolve antiviral 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 staining.
Medical uses
Amylase also has medical applications in the use of
pancreatic enzyme replacement therapy
Pancreatic enzymes, also known as pancreases or pancrelipase and pancreatin, are commercial mixtures of amylase, Pancreatic lipase family, lipase, and protease. They are used to treat malabsorption syndrome due to certain Exocrine pancreatic insu ...
(PERT). It is one of the components in Sollpura (
liprotamase
Pancreatic enzymes, also known as pancreases or pancrelipase and pancreatin, are commercial mixtures of amylase, Pancreatic lipase family, lipase, and protease. They are used to treat malabsorption syndrome due to certain Exocrine pancreatic insu ...
) to help in the breakdown of
saccharides into simple sugars.
Other uses
An inhibitor of alpha-amylase, called
phaseolamin, has been tested as a potential
diet aid.
When used as a
food additive
Food additives are substances added to food to preserve flavor or enhance taste, appearance, or other sensory qualities. Some additives have been used for centuries as part of an effort to preserve food, for example vinegar (pickling), salt (salt ...
, amylase has
E number
E numbers ("E" stands for "Europe") are codes for substances used as food additives, including those found naturally in many foods such as vitamin C, for use within the European Union (EU) and European Free Trade Association (EFTA). Commonly ...
E1100, and may be derived from
pig
The pig (''Sus domesticus''), often called swine, hog, or domestic pig when distinguishing from other members of the genus '' Sus'', is an omnivorous, domesticated, even-toed, hoofed mammal. It is variously considered a subspecies of ''Sus s ...
pancreas or
mold fungi.
Bacilliary amylase is also used in clothing and dishwasher
detergent
A detergent is a surfactant or a mixture of surfactants with cleansing properties when in dilute solutions. There are a large variety of detergents, a common family being the alkylbenzene sulfonates, which are soap-like compounds that are more ...
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.
Hyperamylasemia
Blood serum
Serum () is the fluid and solute component of blood which does not play a role in clotting. It may be defined as blood plasma without the clotting factors, or as blood with all cells and clotting factors removed. Serum includes all proteins not u ...
amylase may be measured for purposes of
medical diagnosis
Medical diagnosis (abbreviated Dx, Dx, or Ds) is the process of determining which disease or condition explains a person's symptoms and signs. It is most often referred to as diagnosis with the medical context being implicit. The information re ...
. A higher than normal concentration may reflect any of several medical conditions, including
acute
Acute may refer to:
Science and technology
* Acute angle
** Acute triangle
** Acute, a leaf shape in the glossary of leaf morphology
* Acute (medicine), a disease that it is of short duration and of recent onset.
** Acute toxicity, the adverse eff ...
inflammation
Inflammation (from la, wikt:en:inflammatio#Latin, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or Irritation, irritants, and is a protective response involving im ...
of the
pancreas
The pancreas is an organ of the digestive system and endocrine system of vertebrates. In humans, it is located in the abdomen behind the stomach and functions as a gland. The pancreas is a mixed or heterocrine gland, i.e. it has both an end ...
(it may be measured concurrently with the more specific
lipase
Lipase ( ) is a family of enzymes that catalyzes the hydrolysis of fats. Some lipases display broad substrate scope including esters of cholesterol, phospholipids, and of lipid-soluble vitamins and sphingomyelinases; however, these are usually tr ...
), perforated
peptic ulcer, torsion of an
ovarian cyst
An ovarian cyst is a fluid-filled sac within the ovary. Often they cause no symptoms. Occasionally they may produce bloating, lower abdominal pain, or lower back pain. The majority of cysts are harmless. If the cyst either breaks open or causes ...
,
strangulation,
ileus,
mesenteric ischemia
Intestinal ischemia is a medical condition in which injury to the large or small intestine occurs due to not enough blood supply. It can come on suddenly, known as acute intestinal ischemia, or gradually, known as chronic intestinal ischemia. The ...
,
macroamylasemia and
mumps
MUMPS ("Massachusetts General Hospital Utility Multi-Programming System"), or M, is an imperative, high-level programming language with an integrated transaction processing key–value database. It was originally developed at Massachusetts Gener ...
. Amylase may be measured in other body fluids, including
urine
Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excretion, excreted from the body through the urethra.
Cel ...
and
peritoneal
The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of mesothe ...
fluid.
A January 2007 study from
Washington University in St. Louis
Washington University in St. Louis (WashU or WUSTL) is a private research university with its main campus in St. Louis County, and Clayton, Missouri. Founded in 1853, the university is named after George Washington. Washington University is r ...
suggests that saliva tests of the enzyme could be used to indicate
sleep deficit
Sleep debt or sleep deficit is the cumulative effect of not getting enough sleep. A large sleep debt may lead to mental or physical fatigue, and can adversely affect one's mood, energy and ability to think clearly.
There are two kinds of sleep d ...
s, as the enzyme increases its activity in correlation with the length of time a subject has been deprived of sleep.
History
In 1831,
Erhard Friedrich Leuchs Erhard is a male German given name and surname, and may refer to:
People
*Erhard of Regensburg, bishop of Regensburg in the 7th century
*Erhard Altdorfer (c. 1480–1561), German Early Renaissance printmaker, painter and architect
*Erhard Arnold Ju ...
(1800–1837) described the
hydrolysis
Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...
of starch by saliva, due to the presence of an enzyme in saliva, "
ptyalin
α-Amylase is an enzyme (EC 3.2.1.1; systematic name 4-α-D-glucan glucanohydrolase) that hydrolyses α bonds of large, α-linked polysaccharides, such as starch and glycogen, yielding shorter chains thereof, dextrins, and maltose:
:Endo ...
", an amylase. it was named after the Ancient Greek name for saliva: - .
The modern history of enzymes began in 1833, when French chemists
Anselme Payen
Anselme Payen (; 6 January 1795 – 12 May 1871) was a French chemist known for discovering the enzyme diastase, and the carbohydrate cellulose.
Biography
Payen was born in Paris. He began studying science with his father when he was a 13-yea ...
and
Jean-François Persoz
Jean-François Persoz (9 June 1805–September 1868) was a French chemist known for discovering the enzyme diastase and on the properties of dextrin. He also wrote a report that coined the name cellulose.
Born in Cortaillod, Persoz studied phy ...
isolated an amylase complex from germinating barley and named it "
diastase A diastase (; from Greek διάστασις, "separation") is any one of a group of enzymes that catalyses the breakdown of starch into maltose. Alpha amylase degrades starch to a mixture of the disaccharide maltose; the trisaccharide maltotriose, ...
". It is from this term that all subsequent enzyme names tend to end in the suffix -ase.
In 1862,
Alexander Jakulowitsch Danilewsky (1838–1923) separated pancreatic amylase from
trypsin
Trypsin is an enzyme in the first section of the small intestine that starts the digestion of protein molecules by cutting these long chains of amino acids into smaller pieces. It is a serine protease from the PA clan superfamily, found in the dig ...
.
Evolution
Salivary amylase
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.
Following the
agricultural revolution 12,000 years ago, human diet began to shift more to plant and animal
domestication in place of
hunting and gathering
A traditional hunter-gatherer or forager is a human living an ancestrally derived lifestyle in which most or all food is obtained by foraging, that is, by gathering food from local sources, especially edible wild plants but also insects, fungi, ...
. 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
The chimpanzee (''Pan troglodytes''), also known as simply the chimp, is a species of great ape native to the forest and savannah of tropical Africa. It has four confirmed subspecies and a fifth proposed subspecies. When its close relative th ...
s and
bonobo
The bonobo (; ''Pan paniscus''), also historically called the pygmy chimpanzee and less often the dwarf chimpanzee or gracile chimpanzee, is an endangered great ape and one of the two species making up the genus '' Pan,'' the other being the comm ...
s, who possess either one or no copies of the gene responsible for producing salivary amylase.
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
The human AMY1C gene encodes the protein Amylase, alpha 1C (salivary).
Amylases are secreted proteins that hydrolyze 1,4-alpha-glucoside bonds in oligosaccharides and polysaccharides, and thus catalyze the first step in digestion of dietary sta ...
'', ''
AMY2A
Pancreatic alpha-amylase is an enzyme that in humans is encoded by the ''AMY2A'' gene.
Amylases are secreted proteins that hydrolyze 1,4-alpha-glucoside bonds in oligosaccharides and polysaccharides, and thus catalyze the first step in digestion ...
'', ''
AMY2B'', and so on.
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
Biaka,
Datog
The Datooga, (''Wamang'ati'' in Swahili), are a pastoralist Nilotic people of based in Manyara Region, south west Arusha Region, and northern Singida Region of Tanzania. In 2000 the Datooga population was estimated to number 87,978.
History
...
, and
Yakuts
The Yakuts, or the Sakha ( sah, саха, ; , ), are a Turkic ethnic group who mainly live in the Republic of Sakha in the Russian Federation, with some extending to the Amur, Magadan, Sakhalin regions, and the Taymyr and Evenk Districts ...
.
[
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.][
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.][
Variations of amylase copy number in dogs mirrors that of human populations, suggesting they acquired the extra copies as they followed humans around.] 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.[
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References
{{Authority control
Chemical pathology
EC 3.2.1
Enzymes
Food additives
Saliva
Enzymes of known structure