The key difference between alpha beta and gamma amylase is that alpha amylase enzyme works by acting on random locations along the starch chain and beta amylase works from the non-reducing end of the polysaccharide by cleaving alpha-1,4 glycosidic bonds, whereas gamma amylase works from the non-reducing end of the polysaccharide by cleaving both alpha-1,4 glycosidic bonds and alpha-1,6 glycosidic bonds.
Amylase is an enzyme that can catalyze the hydrolysis of starch into sugar molecules. This enzyme is present in the saliva of humans and some other mammals.
CONTENTS
1. Overview and Key Difference
2. What is Alpha Amylase
3. What is Beta Amylase
4. What is Gamma Amylase
5. Alpha vs Beta vs Gamma Amylase in Tabular Form
6. Summary –Alpha vs Beta vs Gamma Amylase
What is Alpha Amylase?
Alpha amylase is an enzyme that can hydrolyze alpha bonds of large polysaccharides. These are alpha-linked polysaccharides, including starch and glycogen. This hydrolysis reaction yields shorter chains of dextrin and maltose. This is a major form of amylase that we can find in humans and other mammals. Moreover, we can find it in seeds containing starch, and it is also secreted by many types of fungi. This enzyme is a member of the glycoside hydrolase family 13.
Figure 01: Alpha Amylase Enzyme
Industrially, this enzyme is useful in ethanol production. It can break starch in grains into fermentable sugars. The treatment of cornstarch with the alpha amylase enzyme is the first step in producing high-fructose corn syrup. This process produces shorter chains of oligosaccharide sugars. Furthermore, an alpha amylase enzyme named termamyl is useful in some detergents when dishwashing and using starch-removing detergents.
Moreover, there are different methods we can use to determine the activity of alpha amylase enzyme. The most common way is the starch-iodine test. It is a development of the iodine test. This test depends on the colour change of the starch-iodine complex. The industrially most important test is the Phadebas amylase test.
What is Beta Amylase?
Beta amylase is an enzyme that can catalyze the hydrolysis of alpha-D-glucosidic linkages in polysaccharides, removing maltose units from the polysaccharide. It is an enzyme having the chemical name 4-alpha-D-glucan maltohydrolase.
Figure 02: Beta Amylase
The major substrates of beta amylase are starch, glycogen, and polysaccharides, which produce beta-maltose through an inversion. Moreover, we can find this enzyme in bacteria, fungi, and plants. Among them, bacteria and cereal sources are the most heat-stable forms. The beta amylase enzyme acts from the non-reducing ends of the polysaccharide chains. Starting from that end, this enzyme catalyzes the hydrolysis of second alpha-1,4 glycosidic bond through cleaving off two glucose units, specifically maltose at a time.
When considering the sources of beta amylase, it occurs in an inactive form in pre-seed germination. Most microbes produce this enzyme through degrading extracellular starches. There is no beta amylase in animal tissues, although it can occur in microorganisms that exist within the digestive tract. For this enzyme to work optimally, pH 4.0 – 5.0 is an ideal range.
What is Gamma Amylase?
Gamma amylase is a type of amylase that can cleave alpha 1,6-glycosidic linkages and alpha 1,4-glycosidic bonds in amylose, amylopectin. This cleavage occurs at the non-reducing end. The product of this cleavage is glucose. Among all other forms of amylase enzyme, gamma amylase has the most acidic optimum Ph range. It has an optimal working pH of around 3.0. These gamma amylase enzymes may belong to different glycosidic hydrolase families, including the glycosidic hydrolase 15 family in fungi species, glycosidic hydrolase family 31 in humans, and glycosidic hydrolase 97 in bacteria species.
What is the Difference Between Alpha Beta and Gamma Amylase?
Amylase is an enzyme that can catalyze the hydrolysis of starch into sugar molecules. This enzyme is present in the saliva of humans and some other mammals. The key difference between alpha beta and gamma amylase is that alpha amylase enzyme works by acting on random locations along the starch chain and the beta amylase works from the non-reducing end of the polysaccharide by cleaving alpha-1,4 glycosidic bonds. Whereas, the gamma amylase works from the non-reducing end of the polysaccharide by cleaving both alpha-1,4 glycosidic bonds and alpha-1,6 glycosidic bonds.
The below infographic lists the differences between alpha beta and gamma amylase in tabular form for side by side comparison.
Summary – Alpha vs Beta vs Gamma Amylase
Amylase is an enzyme that can catalyze the hydrolysis of starch into sugar molecules. The key difference between alpha beta and gamma amylase is that alpha amylase enzyme works by acting on random locations along the starch chain and beta amylase works from the non-reducing end of the polysaccharide by cleaving alpha-1,4 glycosidic bonds, whereas gamma amylase works from the non-reducing end of the polysaccharide by cleaving both alpha-1,4 glycosidic bonds and alpha-1,6 glycosidic bonds.
Reference:
1. “The Oxford Companion to Beer Definition of Alpha Amylase.” Craft Beer & Brewing.
Image Courtesy:
1. “Salivary alpha-amylase 1SMD” By Own work. – From PDB entry 1SMD. (Public Domain) via Commons Wikimedia
2. “2xfr b amylase” By A2-33 – Own work (CC BY-SA 3.0) via Commons Wikimedia
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