Table of Contents
- Amylase – Definition
- Classification of Amylase
- Uses
- Clinical Significance
- Frequently Asked Questions
Amylase – Definition
Amylase is an enzyme that occurs naturally in the saliva of some mammals and humans that aids in the process of digestion. It accelerates the breakdown or hydrolysis of starch into simple sugars. The pancreas and the salivary glands mainly synthesise amylase to hydrolyse dietary starch into disaccharides and trisaccharides that are converted into glucose and used as energy.
Amylase was one of the first enzymes to be discovered in the 1800s. It was initially named diastaste but later renamed amylase in the late 20th century.
Classification of Amylase
There are three types of amylases known: alpha, beta and gamma. All three are found in different organisms and catalyse different sites of the starch molecule.
ɑ-Amylase
ɑ-amylases are found in humans, animals, plants, as well as in microbes. They are calcium metalloenzymes that cleave random α-1,4 glycosidic bonds to yield either maltose and maltotriose from amylose chains or glucose, maltose and dextrin from amylopectin chains.
In humans, amylase secreted from the pancreas and salivary gland is ɑ-amylases. Because they can break random bonds in the starch chain, they tend to work more quickly than the 𝛃-amylases. Their optimum pH is 6.7 – 7.0. They are a member of the glycosidic hydrolase family 13.
𝛃-Amylase
The 𝛃-amylases are found in microbes and plants. They hydrolyse the second α-1,4 glycosidic bond in the starch molecule and yield two maltose molecules at a time. They are a member of the glycosidic hydrolase family 14.
At the time of ripening of fruits, the starch is hydrolysed into maltose which gives a sweet taste to the fruits. Their optimum pH is 4.0 – 5.0. 𝛃-amylases are found in seeds in an inactive form prior to germination.
𝛄-Amylase
𝛄-amylases are found in plants and animals. They cleave the last α-1,4 glycosidic bond and the α-1,6 glycosidic bond in the starch molecule to yield glucose molecules. Their optimum pH is 3. They are a member of the glycosidic hydrolase family 15.
Uses
- The enzyme ɑ-amylase finds a great deal of use in brewing liquor and beer that is made from starch. It is achieved through a process of fermentation, where the yeast consumes sugar and yields alcohol.
- In breadmaking, yeasts, which already secrete amylase, break down the starch in the flour into carbon dioxide and ethanol, giving rise to the bread and also adding flavour.
- In molecular biology, amylase can be used as a method of selection for antibiotic gene resistance.
Clinical Significance
The blood serum amylase level is tested for various diagnostic purposes. A higher concentration of amylase (hyperamylasemia) can be indicative of acute pancreatitis, strangulation, peptic ulcer, ileus or mumps.
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Also Read:
- Introduction to Enzymes, Types and Their Applications
- Digestion and Absorption – Important Notes for NEET Biology
- Digestive Enzymes – Amylase, Protease and Lipase
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