Amylase
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Overview
- Amylase is an enzyme that splits polysaccharides
- Serum reference range: 60-180 U/l
Amylase is the name given to glycoside hydrolase enzymes that break down starch into maltose molecules. Although the amylases are designated by different Greek letters, they all act on α-1,4-glycosidic bonds. Under the original name of diastase, amylase was the first enzyme to be found and isolated (by Anselme Payen in 1833).
Classification
α-Amylase
(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.
In human physiology, both the salivary and pancreatic amylases are α-Amylases. They are discussed in much more detail at alpha-Amylase.
β-Amylase
(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 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.
γ-Amylase
(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.
Uses
Amylase enzymes are used extensively in bread making 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 into bread improver thereby making the bread making process faster and more practical for commercial use.
Bacilliary amylase is also used in detergents to dissolve starches from fabrics.
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. [1]
An inhibitor of alpha-amylase called phaseolamin has been tested as a potential diet aid. [1]
Differential Diagnosis of Abnormalities in Amylase
Increased Amylase
- Acute cholecystitis
- Acute pancreatitis
- After endoscopic retrograde cholangio-pancreatography (ECRP)
- Appendicitis
- Ascites
- Bronchial Cancer
- Diabetic Ketoacidosis
- Drugs
- Esophageal Cancer
- Intestinal infarction
- Intestinal obstruction
- Macroamylasemia
- Malignancies
- Ovarian Cancer
- Pancreas abscess
- Pancreas pseudocyst
- Pancreatic neoplasm
- Parotitis
- Penetrating, perforated peptic ulcer
- Peritonitis
- Pulmonary infarction
- Renal failure
- Ruptured ectopic pregnancy
References
Additional Resources
- Burtis, Carl A.; Ashwood, Edward R. (1999). Tietz Textbook of Clinical Chemistry, 3rd ed.. Philadelphia: W. B. Saunders Company, 689-698, 1318. ISBN 0-7216-5610-2.
External links
- Molecule of the month February 2006 at the Protein Data Bank.
- Nutrition Sciences 101 at University of Arizona.
Hydrolase: sugar hydrolases (EC 3.2) | |
|---|---|
| 3.2.1: Glycoside hydrolases | Amylase (Alpha-Amylase) - Chitinase - Lysozyme - Neuraminidase - Galactosidases (Alpha, Beta) - alpha-Mannosidase - Glucuronidase - Hyaluronidase - Pullulanase - Glucocerebrosidase - Galactosylceramidase - Alpha-N-acetylglucosaminidase - Fucosidase - Hexosaminidase - Iduronidase - Disaccharidase (Sucrase/Sucrase-isomaltase/Invertase, Maltase, Trehalase, Lactase) - Glucosidases (Cellulase, Alpha-glucosidase, Beta-glucosidase, Debranching enzyme) |
| 3.2.2: Hydrolysing N-Glycosyl compounds | DNA glycosylases: Oxoguanine glycosylase |
de:Amylase et:Amülaas eo:Amelazo fr:Amylase it:Alfa-amilasi he:עמילאז nl:Amylase ja:アミラーゼ no:Amylasesimple:Amylase fi:Amylaasi sv:Amylas uk:Амілаза
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
