Dictionary:
am·y·lase (ăm'ə-lās', -lāz') ![]() |
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An enzyme which breaks down (hydrolyzes) starch, the reserve carbohydrate in plants, and glycogen, the reserve carbohydrate in animals, into reducing fermentable sugars, mainly maltose, and reducing nonfermentable or slowly fermentable dextrins. Amylases are classified as saccharifying (β-amylase) and as dextrinizing (α-amylases). The α- and β-amylases are specific for the α- and β-glucosidic bonds which connect the monosaccharide units into large aggregates, the polysaccharides. The α-amylases are found in all types of organs and tissues, whereas β-amylase is found almost exclusively in higher plants. See also Carbohydrate; Enzyme; Glycogen; Maltose.
In animals the highest concentrations of amylase are found in the saliva and in the pancreas. Salivary amylase is also known as ptyalin and is found in humans, the ape, pig, guinea pig, squirrel, mouse, and rat.
In plants, starch is broken down during the germination of seeds (rich in starch) by associated plant enzymes into sugars. These constitute the chief energy source in the early development of the plant. β-Amylase occurs abundantly in seeds and cereals such as malt. It also is found in yeasts, molds, and bacteria.
| Food and Nutrition: amylases |
Enzymes that hydrolyse starch and glycogen. α-Amylase (dextrinogenic amylase or diastase) acts to produce small dextrin fragments from starch, while β-amylase (maltogenic amylase) liberates maltose, some free glucose, and isomaltose from the branch points in amylopectin.
Salivary amylase (sometimes called by its obsolete name of ptyalin) and pancreatic amylase are both α-amylases. See also Z-enzyme.
| Dental Dictionary: amylase |
An enzymatic protein essential for changing starches into sugars.
| Columbia Encyclopedia: amylase |
| Veterinary Dictionary: amylase |
An enzyme that catalyzes the hydrolysis of starch into simpler compounds. The α-amylases occur in animals and include pancreatic and salivary amylase; the β-amylases occur in higher plants. Measurement of serum α-amylase activity is an important diagnostic test for acute pancreatitis and acute attacks of chronic pancreatitis.
| Wikipedia: Amylase |
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An amylase is an enzyme that breaks starch down into sugar. Amylase is present in human saliva, where it begins the chemical process of digestion. Foods that contain much starch but little sugar, such as rice and potato, taste slightly sweet as they are chewed because amylase turns some of their starch into sugar in the mouth. The pancreas also makes amylase (alpha amylase) to hydrolyse dietary starch into di- and trisaccharides which are converted by other enzymes to glucose to supply the body with energy. Plants and some bacteria also produce amylase. As diastase, amylase was the first enzyme to be discovered and isolated (by Anselme Payen in 1833).[citation needed] Specific amylase proteins are designated by different Greek letters. All amylases are glycoside hydrolases and act on α-1,4-glycosidic bonds. It will start to denature at around 60C.
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(EC 3.2.1.1 ) (CAS# 9014-71-5) (alternate names: 1,4-α-D-glucan glucanohydrolase; glycogenase) The α-amylases are calcium metalloenzymes, completely unable to function in the absence of calcium. By acting at random locations along the starch chain, α-amylase breaks down long-chain carbohydrates, ultimately yielding maltotriose and maltose from amylose, or maltose, glucose and "limit dextrin" from amylopectin. Because it can act anywhere on the substrate, α-amylase tends to be faster-acting than β-amylase. In animals, it is a major digestive enzyme and its optimum pH is 6.7-7.0. [1]
In human physiology, both the salivary and pancreatic amylases are α-Amylases. They are discussed in much more detail at alpha-Amylase.
Also found in plants (adequately) , fungi (ascomycetes and basidiomycetes) and bacteria (Bacillus).
(EC 3.2.1.2 ) (alternate names: 1,4-α-D-glucan maltohydrolase; glycogenase; saccharogen amylase) Another form of amylase, β-amylase is also synthesized by bacteria, fungi, and plants. 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 sugar, resulting in the sweet flavor of ripe fruit.
Both α-amylase and β-amylase are present in seeds; β-amylase is present prior to germination, whereas α-amylase and proteases appear once germination has begun. Cereal grain amylase is key to the production of malt. Many microbes also produce amylase to degrade extracellular starches. Animal tissues do not contain β-amylase, although it may be present in microrganisms contained within the digestive tract.
(EC 3.2.1.3 ) (alternative names: Glucan 1,4-α-glucosidase; amyloglucosidase; Exo-1,4-α-glucosidase; glucoamylase; lysosomal α-glucosidase; 1,4-α-D-glucan glucohydrolase) In addition to cleaving the last α(1-4)glycosidic linkages at the nonreducing end of amylose and amylopectin, yielding glucose, γ-amylase will cleave α(1-6) glycosidic linkages. Unlike the other forms of amylase, γ-amylase is most efficient in acidic environments and has an optimum pH of 3.
Amylase enzymes finds use in bread making 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 alcohol and CO2. This imparts flavour and causes the bread to rise. While Amylase enzymes 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 sour dough. Modern bread making techniques have included amylase enzymes (often in the form of malted barley) into bread improver thereby making the bread making process faster and more practical for commercial use.[2]
When used as a food additive Amylase has E number E1100, and may be derived from swine pancreas or mould mushroom.
Bacilliary amylase is also used in clothing and dishwasher detergents to dissolve starches from fabrics and dishes.
Workers in factories that work with amylase for any of the above uses are at increased risk of occupational asthma. 5-9% of bakers have a positive skin test, and a fourth to a third of bakers with breathing problems are hypersensitive to amylase. [3]
An inhibitor of alpha-amylase called phaseolamin has been tested as a potential diet aid. [4]
Blood serum amylase may be measured for purposes of medical diagnosis. A normal concentration is in the range 21-101 U/L. A higher than normal concentration may reflect one of several medical conditions, including acute inflammation of the pancreas, macroamylasemia, perforated peptic ulcer, and mumps. Amylase may be measured in other body fluids, including urine and peritoneal fluid.
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In 1831 Erhard Friedrich Leuchs (1800-1837) described the diastatic action of salivary ptyalin (amylase) on starch.[5] The modern history of enzymes began in 1833 when French chemists described the isolation of an amylase complex from germinating barley and named it diastase.[6] In 1862 Danielewski separated pancreatic amylase from trypsin.[7]
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| Translations: Amylase |
Nederlands (Dutch)
amylase (zetmeel afbrekend enzym)
Français (French)
n. - (Physiol) amylase
Deutsch (German)
n. - (chem.) Amylase
Ελληνική (Greek)
n. - (χημ.) αμυλάση
Português (Portuguese)
n. - amilase (f) (Quím.)
Español (Spanish)
n. - amilasa
中文(简体)(Chinese (Simplified))
淀粉酵素
中文(繁體)(Chinese (Traditional))
n. - 澱粉酵素
العربيه (Arabic)
(الاسم) الأميليز : خميره في اللعاب والعصاره البنكرياسيه تساعد على تحويل النشا الى سكر
עברית (Hebrew)
n. - תסס עמילן (אנזים), אנזים ההופך עמילן וגליקוגן (חומר בכבד) לסוכרים פשוטים
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| AMS | |
| ptyalin | |
| –ase (suffix) |
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