Amylase

Amylase is a type of enzyme that catalyses the breakdown of starch (Latin amylum) into sugars. Amylase is found in human and some other mammalian saliva, where it initiates the chemical process of digestion. Foods high in starch but low in sugar, such as rice and potatoes, may acquire a mild sweetness after chewing as amylase converts some of their starch to sugar. Amylase (alpha amylase) is produced by the pancreas and salivary gland to hydrolyze dietary starch into disaccharides and trisaccharides that are then converted to glucose by other enzymes to provide energy to the body. Amylase is also produced by plants and some microorganisms. Different Greek letters are assigned to different amylase proteins. Amylases are all glycoside hydrolases that catalyse the hydrolysis of 1,4-glycosidic bonds.

Classification

α-Amylase

α-amylases (EC 3.2.1.1) (CAS 9014-71-5) are calcium metalloenzymes (other names: 1,4–D-glucan glucanohydrolase; glycogenase). The amylase degrades long-chain saccharides at random sites along the starch chain, ultimately generating maltotriose and maltose from amylose or maltose, glucose, and “limit dextrin” from amylopectin. They are members of the glycoside hydrolase family 13 (glycoside hydrolase family 13).

Due to its ability to function anywhere on the substrate, -amylase is typically faster acting than -amylase. It is a significant digestive enzyme in animals, with an optimal pH of 6.7–7.0.

Both salivary and pancreatic amylases are -amylases in human physiology.

Plants, fungi (ascomycetes and basidiomycetes), and bacteria all have the -amylase form (Bacillus).

β-Amylase

Bacteria, fungi, and plants also generate another type of amylase, β-amylase (EC 3.2.1.2) (other names: 1,4–D-glucan maltohydrolase; glycogenase; saccharogenic amylase). Amylase catalyses the hydrolysis of the second -1,4 glycosidic bond from the non-reducing end, cleaving off two glucose units (maltose) at a time. -amylase converts starch to maltose during fruit ripening, resulting in the sweet flavour of ripe fruit. They are members of the glycoside hydrolase family 14 (glycoside hydrolases).

Both α-amylase and β-amylase are present in seeds; -amylase is present in an inactive state prior to germination, whereas -amylase and proteases become active once germination begins. Numerous microorganisms produce amylase as well, which is used to break down extracellular carbohydrates. Although -amylase is not found in animal tissues, it may be present in bacteria found in the digestive tract. -amylase performs best in a pH range of 4.0–5.0.

γ-Amylase

γ-Amylase (EC 3.2.1.3) (other names: glucan 1,4-a-glucosidase; amyloglucosidase; exo-1,4—glucosidase; glucoamylase; lysosomal -glucosidase; 1,4–D-glucan glucohydrolase) will cleave (1–6) glycosidic bonds, as well as the Because it is most active at pH 3, the -amylase has the most acidic optimal pH of all amylases. They are members of several different glycoside hydrolase families, including glycoside hydrolase family 15 in fungi, glycoside hydrolase family 31 in human MGAM, and glycoside hydrolase family 97 in bacteria.

Uses

Fermentation

α- and β-amylases are necessary for the production of beer and liquor from sugars obtained from starch. Yeast consumes carbohydrates and excretes ethanol during fermentation. The sugars present at the start of fermentation in beer and some liquors were created by “mashing” grains or other starch sources (such as potatoes). Malted barley is combined with hot water to make a “mash,” which is kept at a specific temperature to allow the amylases in the malted grain to convert the starch in the barley into sugars. The activity of alpha or beta amylase is optimized at different temperatures, resulting in diverse combinations of fermentable and non fermentable carbohydrates. A brewer can alter the alcohol concentration, texture, fragrance, and flavor of a finished beer by adjusting the mash temperature and grain-to-water ratio.

The conversion of starch to sugar begins with the brewer chewing grain to mix it with saliva in some traditional techniques of making alcoholic beverages.

Some traditional drinks, such as chhaang in the Himalayas, chicha in the Andes, and kasiri in Brazil and Suriname, are still made in this manner at home.

Flavour Additive

Amylases are needed in breadmaking and for the breakdown of complex carbohydrates such as starch (present in flour). Yeast then feeds on these simple sugars and transforms them to ethanol and carbon dioxide as waste products. This provides flavour to the bread and causes it to rise. While amylases are naturally occurring in yeast cells, it takes time for the yeast to manufacture enough of these enzymes to effectively break down the starch in the bread. This is why long fermented doughs such as sourdough are desirable. Modern bread making processes incorporate amylases (typically in the form of malted barley) into the bread improver, which speeds up and simplifies the process for commercial use.

α-Amylase is a common component in commercially packaged flour. Bakers who have been exposed to amylase-enriched flour for an extended period of time are at risk of acquiring dermatitis or asthma.

Molecular biology

In molecular biology, the presence of amylase can serve as an alternative technique of selecting for effective integration of a reporter construct in addition to antibiotic resistance. As reporter genes are flanked by homologous sections of the structural gene for amylase, effective integration will disrupt the amylase gene and inhibit starch degradation, which is easily observable through iodine staining.

Medical uses

Amylase is also used medically in pancreatic enzyme replacement therapy (PERT). It is a component of Sollpura (liprotamase) that contributes to the breakdown of disaccharides into simple sugars.

Other Uses

1. Phaseolamin, an alpha-amylase inhibitor, has been studied as a possible diet help.
2. Amylase bears the E number E1100 when used as a food additive and may be generated from pig pancreatic or mould fungus.
3. Bacillary amylase is also used to break down starches from fabrics and dishes in clothing and dishwasher detergents.
4. Workers exposed to amylase for any of the aforementioned purposes are at an elevated risk of occupational asthma. Between 5% and 9% of bakers have a positive skin test, and between a fourth and a third of bakers with breathing issues are amylase hypersensitive.

Hyperamylasemia

Amylase levels in the blood serum may be determined for diagnostic purposes. A greater than normal concentration may indicate a variety of medical problems, including acute pancreatitis (it can be evaluated concurrently with the more specific lipase), perforated peptic ulcer, ovarian cyst torsion, strangulation, ileus, mesenteric ischemia, macroamylasemia, and mumps. Amylase levels can also be determined in various bodily fluids, such as urine and peritoneal fluid.

According to a January 2007 study from Washington University in St. Louis, saliva testing for the enzyme could be used to detect sleep deprivation, as the enzyme’s activity increases in correlation with the duration of sleep deprivation.

Conclusion

Amylase is an enzyme which helps to break down starch into sugars. Amylase is found in the saliva of humans and other mammals, where it starts the chemical process of digestion. Rice and potatoes, which are high in starch but low in sugar, may develop a moderate sweetness after chewing when amylase converts some of the starch to sugar.