AMYLASE

Amylase = AMY

CAS Number: 9000-90-2, 9000-85-5
EC Number: 3.2.1.1

An amylase is an enzyme that catalyses the hydrolysis of starch (Latin amylum) into sugars. 
Amylase is present in the saliva of humans and some other mammals, where Amylases begins the chemical process of digestion. 
Foods that contain large amounts of starch but little sugar, such as rice and potatoes, may acquire a slightly sweet taste as they are chewed because amylase degrades some of their starch into sugar.

The pancreas and salivary gland make amylase (alpha amylase) to hydrolyse dietary starch into disaccharides and trisaccharides which are converted by other enzymes to glucose to supply the body with energy. 
Plants and some bacteria also produce amylase. 
Specific amylase proteins are designated by different Greek letters. 
All amylases are glycoside hydrolases and act on α-1,4-glycosidic bonds.

Amylase is a digestive enzyme predominantly secreted by the pancreas and salivary glands and found in other tissues in very small levels. 
Amylase was first described in the early 1800s and is considered one of the first enzymes in history to be scientifically investigated. 
Amylases was initially termed as diastaste but was later renamed amylase in the early 20th century.

Amylases' main function is to hydrolyze the glycosidic bonds in starch molecules, converting complex carbohydrates to simple sugars. 
There are three main classes of amylase enzymes; Alpha-, beta- and gamma-amylase, and each act on different parts of the carbohydrate molecule. 
Alpha-amylase can be found in humans, animals, plants, and microbes. 

Beta-amylase is found in microbes and plants. 
Gamma-amylase is found in animals and plants. 
This article will focus on alpha-amylase and Amylasess applications.

In 1908, a study by Wohlgemuth identified the presence of amylase in urine, and this subsequently led to the use of amylase as a diagnostic laboratory test. 
Amylase is a commonly ordered test along with lipase, especially in the setting of suspected acute pancreatitis.

amylase, any member of a class of enzymes that catalyze the hydrolysis (splitting of a compound by addition of a water molecule) of starch into smaller carbohydrate molecules such as maltose (a molecule composed of two glucose molecules). 
Three categories of amylases, denoted alpha, beta, and gamma, differ in the way they attack the bonds of the starch molecules.

Alpha-amylase is widespread among living organisms. 
In the digestive systems of humans and many other mammals, an alpha-amylase called ptyalin is produced by the salivary glands, whereas pancreatic amylase is secreted by the pancreas into the small intestine.
The optimum pH of alpha-amylase is 6.7–7.0.

Ptyalin is mixed with food in the mouth, where Amylases acts upon starches. 
Although the food remains in the mouth for only a short time, the action of ptyalin continues for up to several hours in the stomach—until the food is mixed with the stomach secretions, the high acidity of which inactivates ptyalin. 
Ptyalin’s digestive action depends upon how much acid is in the stomach, how rapidly the stomach contents empty, and how thoroughly the food has mixed with the acid. 
Under optimal conditions as much as 30 to 40 percent of ingested starches can be broken down to maltose by ptyalin during digestion in the stomach.

When food passes to the small intestine, the remainder of the starch molecules are catalyzed mainly to maltose by pancreatic amylase. 
This step in starch digestion occurs in the first section of the small intestine (the duodenum), the region into which the pancreatic juices empty. 
The by-products of amylase hydrolysis are ultimately broken down by other enzymes into molecules of glucose, which are rapidly absorbed through the intestinal wall.

Beta-amylases are present in yeasts, molds, bacteria, and plants, particularly in the seeds. 
They are the principal components of a mixture called diastase that is used in the removal of starchy sizing agents from textiles and in the conversion of cereal grains to fermentable sugars. 
Beta-amylase has an optimum pH of 4.0–5.0.

Amylases are a group of enzymes that hydrolyze starch. 
Many enzymes act on starch or on the oligosaccharides derived from them. 
Nineteen enzymes have been classified as belonging to the microbial amylase group: hydrolases (EC 3) such as α-amylase, β-amylase, glucoamylase, α-glucosidase, debranching enzymes and transferases (EC 2) such as CGTase, 4-α-glucanotransferase, and a branching enzyme. 

First, the catalytic properties of each of the 19 enzymes were described to clarify the differences among them and their microbial sources. 
Next, the structural features of these enzymes were described based on CAZy classification. 
Special efforts were made to correlate the unique catalytic property (EC number) of each enzyme with Amylasess unique structural property (glycoside hydrolase family or subfamily). 
The structures of four enzymes – Taka-amylase (representative of α-amylase), CGTase, β-amylase, and glucoamylase – were explained with a focus on their domain structures, catalytic site structures, identification and position of two catalytic residues, and the catalytic mechanisms realized by these structures. 

Explanation of the exo- or endo-acting mechanisms and the retaining or inverting mechanisms of the enzymes is attempted based on their structural features. 
Finally, industrial applications of amylase were reviewed with an emphasis on the role of α-amylase and glucoamylase in the starch saccharification industry. 
There have been recent developments in trehalose production and other cyclic glucans.

α-Amylase (1,4-α-D-glucan-glucanohydrolase, EC 3.2.1.1) is the primary digestive enzyme acting on starch or glycogen and is present in plants, animals, bacteria and fungi.  
Starch from plants is a high molecular weight polymer of glucose. 
Amylases is made up of amylose, a straight-chain α-1,4 linked polymer of about 105units and amylopectin, a branched chain polymer with α-1,4 linked glucose with branch points made up of α-1,6 linkages that contains in total about 106 units of glucose. 
Glycogen from animals is similar to amylopectin in structure but is smaller. 

α-Amylase cleaves the α-1,4 linkage when Amylases is not next to a branch point or terminal glucose residue. 
Thus Amylasess products are maltose (2 glucose residues), maltotriose (3 glucose residues) and α-limit dextrins (5-6 residues which contain a branch point). 
In vertebrates, these are further cleaved to monosaccharides by the intestinal brush border enzymes isomaltase and maltase (glucoamylase) which hydrolyze the α-1,6 and α-1,4 bonds respectively. 
Studies show that hydrolysis and not monosaccharide absorption is the rate limiting step in complex carbohydrate absorption in humans.

In animals α-amylase occurs in pancreas, parotid, liver, serum, urine and occasionally in smaller amounts in other tissues or tumors; the major salivary and pancreatic amylase proteins are very similar. 
Salivary amylase initiates carbohydrate digestion in the mouth and pancreatic amylase is the main enzyme for luminal digestion of carbohydrate in the small intestine.  
Human pancreatic α-amylase is synthesized as a protein of 57 KDa for which the cDNA predicts a protein of 512 amino acids. 

This includes a signal sequence; amylase isolated from human pancreatic juice has 496 amino acids. 
In various species the reported molecular weight for amylase is 50-57 kDa and consists of a single chain protein with one carbohydrate (some species have an isoform with none) and an isoelectric point of 7.1. 
Human pancreatic juice amylase has no sugar groups and exists as two isoforms of pI 7.2 and 6.6 termed HPA I and HPA II. 
Five disulfide bridges have been described in porcine pancreatic amylase (44) and most species have one or two free sulphydryl groups.

Salivary amylase is coded for by the AMY1 gene and pancreatic amylase by AMY2; a third form present in some tumors is termed AMY2B. 
The evolution of the amylase gene family has been traced with a retroviral insertion into the promotor of a pancreatic amylase gene diverting Amylases to become a salivary gene. 
Amylase is a multigene family with multiple genes and pseudogenes on chromosome 1 in humans and chromosome 3 in mice. 
While most inbred mouse strains express a single species of amylase, some strains (A/J, CE/J) and most wild mice have multiple forms. 
Interestingly, individuals from agricultural societies that consume high starch diets have a higher copy number of salivary amylase genes and a high copy number leads to more protein and increased perception of oral starch.

The structure of human amylase protein is known and contains three domains termed A, B, and C starting at the amino terminal. 
The active site is located the A domain; calcium binds to the B domain and may stabilize the active site. 
The C domain is a globular domain of unknown function. 

Some amylases including human pancreatic amylase are allosterically activated by chloride which modulates the pH optima and the maximal activity.
The active center of amylase contains 5 subsites which bind different glucose residues in the substrate. 
Current understanding of the enzymatic mechanism for glycosidases in reviewed in.

Kinetic evidence supports additional carbohydrate binding sites. 
Some of these are surface binding sites which help the amylase bind to starch granules. 
The rate of starch digestion also depends on the structure of the starch which has been classified as rapidly digested, slowly digested, and resistant starch. 

Digestion of starch can also be affected by cooking which can break down starch granules to soluble starch. 
Studies of the enzymatic mechanism have also benefited from the existence of a large family of plant α-amylase inhibitory proteins.  
The best studied of these are from beans and the structure of the enzyme-inhibitor complex has been determined. 

More potent inhibitors have been derived from pseudooligosaccarides of which one, the pseudotetrasacharide, acarbose has been approved for clinical use. 
The crystal structure of pig amylase complexed with acarbose has been reported. 
These pseudooligosaccaride inhibitors, in contrast to the proteinaceous inhibitors, block all glucosidases including intestinal brush border enzymes as well as amylase.

Multiple pancreatic enzymes including amylase are found absorbed to the surface of the duodenal mucosa although they could be washed off with high salt. 
Amylase, however, was shown to specifically bind to N-linked oligosaccharides of brush border glycoproteins and that binding enhanced amylase activity. 
Specific glycoproteins binding amylase have been identified as sucrase-isomaltase (SI) and SGLT1. 

This binding enhanced the activity of SI as well as that of amylase but inhibited the activity of SGLT1. 
The authors proposed that this enhances digestion but prevents too rapid absorption of glucose.  
After binding to brush border proteins amylase is internalized into enterocytes restoring glucose uptake.

Alpha amylase is an oligosaccharide endoglycosidase, an enzyme that cleaves an internal glycosidic bond within a poly or oligosaccharide. 
In the case of alpha amylase, Amylases is the 1,4 linkage between two glucose moieties, cleaving the C-O bond between the C1 carbon and the oxygen, although which 1,4 linkage is cleaved is random.

Alpha amylase requires calcium for activity, although complete activity only occurs in the presence of certain anions such as Cl-, Phosphate and others. 
Although many tissues can produce alpha amylase, the forms found in serum are most often from the pancreas and salivary glands. 
Several isoenzymes have been detected and characterized from these tissue sources. 

Alpha amylases can be found in a variety of body fluids and they are some of the few enzymes that can be found in urine from healthy individuals. 
The main purpose in testing amylase, especially when the appropriate symptoms are present, is to diagnose pancreatitis and other primary and secondary pancreatic pathologies. 
This can be made more specific by testing for amylase isoenzymes specific to the pancreas. 
However total amylase is still a very valuable diagnostic tool.

There is some evidence to suggest that lipase might be a superior indicator of pancreatitis. 
In practice, both enzymes are often measured. 
Amylase may also play a role in diagnosing cancers other than pancreatic cancer, such as multiple myeloma and ovarian cancer, although Amylases appears that at least in some of these cases the salivary form may be the more important form of amylase.

Due to the non-specific nature of amylase, many substrates can be used and in the past this often resulted in considerable variability in measuring amylase, depending on which type of reagent was used. 
As a response, large substrates such as starch have been replaced with smaller, more consistent oligosaccharides. 
Although no useful spectrophotometric changes occur during the amylase catalyzed hydrolysis of these glycosidic bonds, the release of glucose can be coupled to an enzyme such as hexokinase. 

This uses ATP to phosphorylate glucose to produce glucose-6-phosphate (G6P). 
This product can then be coupled to the enzyme glucose-6-phosphate dehydrogenase which uses NAD+ to oxidize G6P. 
The conversion of NAD+ to NADH can be monitored at 340 nm.

An enzyme in the saliva and pancreatic juice that catalyzes the hydrolysis (breaking down) of starch, glycogen and related polysaccharides into more simple and readily usable forms of sugar. 
Amylases cleaves the α (1-4) glycosidic linkages.

Supplement
The amylase is produced and secreted by salivary glands and pancreas to aid in the chemical digestion of foodstuff (such as starch).
Amylase is also present in other organisms such as molds, bacteria, yeasts and plants. 
In plants, the amylase can be found in seeds to break down starch into sugar to be used by the embryo to induce growth.

Amylase is an enzyme that is used to turn starches into sugars. 
Amylases is found in human saliva and Amylasess presence kick-starts the digestion process. 
Amylases is also found in the pancreas and salivary gland and plays an important role in the conversion of dietary starches into glucose for energy in the human body. 

Amylase in Digestion
As soon as food enters your mouth, Amylases starts the process of digestion. 
Food needs to be broken down into smaller nutrients so that the body can store or utilize Amylases. 
Your body produces specialized enzymes that work on digesting the different types of foods you consume. 
Amylase is an enzyme produced in the mouth and pancreas that breaks down carbohydrates into smaller molecules.

The Role of Amylase in the Mouth
During digestion, carbohydrates start out as polysaccharides, which are large starch molecules that are broken down into disaccharides, which are two, linked-sugar molecules. 
Disaccharides are then further broken down into even smaller simple sugars, known as monosaccharides that are then absorbed into the blood so that the body can then use them. 
When you start chewing, food is mechanically broken down into smaller pieces. 

You also produce saliva, which contains amylase that mixes with your food. 
Amylase is a digestive enzyme that chewing activates and which hydrolyzes or breaks downs starch into monosaccharides. 
Amylase breaks down starch in your mouth into a maltose, a disaccharide, which is made up of two glucose molecules.

The Role of Amylase in the Stomach
As you swallow, carbohydrate digestion continues in your stomach as the chewed food mixed with amylase. 
Your stomach does not produce any additional amylase. 

Your stomach contains gastric juices that work on digesting other nutrients in your food. 
The amylase that entered with your chewed food continues to break down starch into maltose. 
From the stomach, food is then passed into the small intestine where digestion continues.

The Role of Amylase in the Pancreas
As the food passes along in the digestive system, Amylases is broken down into even smaller molecules before the body can use Amylases as energy. 
The pancreas also produces the enzyme amylase that is released into the duodenum of the small intestines. 

Amylase produced here breaks down the remaining polysaccharides and disaccharides into monosaccharides, which completes the digestion of carbohydrates. 
Glucose, a monosaccharide, is the result of carbohydrate digestion. 
In the small intestine, glucose is then absorbed into the blood that the body will use for energy. 
Your body uses glucose as fuel for all your bodily processes.

Blood Serum Amylase
Amylase is present in your blood in small amounts; this is normal. 
If your pancreas has been injured, inflamed or blocked, however, amylase is released into the blood rather than the duodenum, which results in elevated blood-serum amylase levels. 

A blood test can test, diagnose or monitor pancreatic problems. 
Health concerns related to elevated amylase in the blood include acute pancreatitis, chronic pancreatitis, pancreatic pseudocyst, or blockage of the duct that carries amylase from the pancreas to the small intestine or gallstones. 
Symptoms usually related to a pancreas disorder can include abdominal pain, nausea, fever or loss of appetite.

If your amylase level is high, Amylases might indicate a problem in your pancreas. 
A low amylase level may suggest a pancreas, liver or kidney problem, or cystic fibrosis.

Amylase is a hydrolytic enzyme that breaks down starch into dextrins and sugars. 
Amylases’s made up of a family of starch-degrading enzymes that include:
Alpha-amylase
Beta-amylase

Amyloglucosidase or glucoamylase
Pullulanase
Maltogenic amylase
Amylases can work at the same time in perfect synergy. 
They are key ingredients that extend the shelf-life of bread, working as fermentation improvers.

α-Amylase is a protein enzyme EC 3.2.1.1 that hydrolyses alpha bonds of large, alpha-linked polysaccharides, such as starch and glycogen, yielding glucose and maltose. 
Amylases is the major form of amylase found in Humans and other mammals. 
Amylases is also present in seeds containing starch as a food reserve, and is secreted by many fungi.

Amylase is an enzyme that catalyzes the hydrolysis of starch into simple sugars such as glucose and mannose. 
Amylases may also hydrolyze oligosaccharides derived from starch. 
Amylases are glycoside hydrolases that act on a-1,4-glycosidic bonds. 
Alpha-amylase is found in plants, animals, microbes, and humans, while beta-amylase is found in microbes and plants and gamma-amylase in microbes and animals. 

Blood amylase measurements are used to indicate pancreatic function. 
Amylase can be used in biochemical assays, starch tests, digestion studies, and fermentation processes. 
Disruption of the amylase gene in a recombinant construct is also a method of selecting for successful integration events. 
Visit the supplier page for more information, including enzyme activity.

Enzymology
α-Amylase, an endoenzyme, preferentially cleaves interior α-1,4 linkages and has very low activity against the bonds of terminal glucose units. 
Additionally, Amylases cannot hydrolyze the α-1,6 linkages in amylopectin. 
The resulting products of amylase acting on starch, referred to as dextrins, are α-1,4-linked glucose dimers (maltose), α-1,4-linked glucose trimers (maltotriose), and branched oligosaccharides of 6 to 8 glucose units that contain both α-1,6 and α-1,4 linkages (limit dextrins). 
Starch digestion can begin in the mouth and in a swallowed bolus of food, but primarily occurs in the lumen of the upper small intestine. 
Digestion of starch is completed in the intestine by the brush border enzymes, maltase and isomaltase.

The active site of α-amylase contains multiple subsites, each of which is capable of binding one glucose residue of the substrate. 
The porcine and human enzymes appear to have five subsites, and subsite three is probably the catalytic site. 
Substrates can bind with the first glucose residue in subsite one or two so that cleavage can occur between the first and second or second and third residues. 

During a single enzyme–substrate encounter, multiple glucose bonds are cleaved. 
Three acidic residues, one glutamic acid and two aspartic acids, are thought to be the catalytic residues. 
The glutamic acid is believed to be the proton donor and one of the aspartic acids acts as a nucleophile. 
α-Amylase has an absolute requirement for calcium ions and is activated by anions such as chloride, bromide, iodide, or fluoride. 

Heavy metals inhibit the enzyme. 
The importance of serum amylase levels in the diagnosis of acute pancreatitis has generated widespread interest in Amylasess assay. 
Amylase is most commonly measured by absorbance or fluorescence assays in which a labeled substrate is cleaved.

Human amylase is secreted by both the pancreas and salivary glands. 
These enzymes digest starch and glycogen in the diet. 
Human salivary and pancreatic amylases have identical enzyme activities. 

However, they differ in molecular weight, carbohydratecontent, and electrophoretic mobility.
Salivary amylase initiates digestion in the mouth and may account for a significant portion of starch and glycogen digestion because Amylases is transported with the meal into the stomach and small intestine, where Amylases continues to have activity. 
In the stomach, the amylase activity is protected from secreted gastric acid by buffering from the meal and by the protected alkaline environment of salivary and gastric mucus. 
The action of both salivary and pancreatic amylase is to hydrolyze 1,4-glycoside linkages at every other junction between carbon 1 and oxygen. 

The products of amylase digestion are maltose and maltotriose (2- and 3-α-1,4–linked molecules, respectively) and α-dextrins containing 1,6-glycosidic linkages, because 1,6-glycosidic linkages in starch cannot be hydrolyzed by amylase. 
The brush-border enzymes of the enterocyte complete hydrolysis of the products of amylase digestion to glucose. 
The final product, glucose, is transported across the intestinal absorptive epithelial cell by a Na+-coupled transport.

Pancreatic α-amylase is produced by the pancreatic acinar cells and released into the duodenum. 
Amylases is a major molecule of pancreatic fluid.

Discovered and isolated by Anselme Payen in 1833, amylase was the first enzyme to be discovered. 
Amylases are hydrolases, acting on α-1,4-glycosidic bonds. 
They can be further subdivided into α,β and γ amylases.
α-Amylase (AAM) is an enzyme that acts as a catalyst for the hydrolysis of α-linked polysaccharides into α-anomeric products. 

The enzyme can be derived from a variety of sources, each with different characteristics. 
α-Amylase found within the human body serves as the enzyme active in pancreatic juice and saliva. 
α-Amylase is not only essential in human physiology but has a number of important biotechnological functions in various processing industries. 
β/α amylase (BAAM) is a precursor protein which is cleaved to form the β-amylase and α-amylase after secretion. 

β amylase (BAM) acts at the non-reducing chain ends and liberate only β-maltose. 
γ amylase (GAM) acts at the non-reducing chain ends of amylose and amylopectin and liberates glucose. 
Pullulanase hydrolyses the α-1,6 glucoside linkage in starch, amylopectin, pullulan and related oligosaccharides.
For α-amylase see Raghad zoubi
See also Amylase (Hebrew).

α-Amylase
The α-amylases (CAS 9014-71-5) (alternative names: 1,4-α-D-glucan glucanohydrolase; glycogenase) are calcium metalloenzymes. 
By acting at random locations along the starch chain, α-amylase breaks down long-chain saccharides, ultimately yielding either maltotriose and maltose from amylose, or maltose, glucose and "limit dextrin" from amylopectin. 
They belong to glycoside hydrolase family 13.

Because Amylases can act anywhere on the substrate, α-amylase tends to be faster-acting than β-amylase. 
In animals, Amylases is a major digestive enzyme, and Amylasess optimum pH is 6.7–7.0.

In human physiology, both the salivary and pancreatic amylases are α-amylases.
The α-amylase form is also found in plants, fungi (ascomycetes and basidiomycetes) and bacteria (Bacillus).

β-Amylase
Another form of amylase, β-amylase (alternative names: 1,4-α-D-glucan maltohydrolase; glycogenase; saccharogen 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 maltose, resulting in the sweet flavor of ripe fruit. 
They belong to glycoside hydrolase family 14.

Both α-amylase and β-amylase are present in seeds; β-amylase is present in an inactive form prior to germination, whereas α-amylase and proteases appear once germination has begun. 
Many microbes also produce amylase to degrade extracellular starches. 
Animal tissues do not contain β-amylase, although Amylases may be present in microorganisms contained within the digestive tract. 
The optimum pH for β-amylase is 4.0–5.0.

γ-Amylase
γ-Amylase (alternative names: Glucan 1,4-a-glucosidase; amyloglucosidase; exo-1,4-α-glucosidase; glucoamylase; lysosomal α-glucosidase; 1,4-α-D-glucan glucohydrolase) will cleave α(1–6) glycosidic linkages, as well as the last α-1,4 glycosidic bond at the nonreducing end of amylose and amylopectin, yielding glucose. 
The γ-amylase has the most acidic optimum pH of all amylases because Amylases is most active around pH 3. 
They belong to a variety of different GH families, such as glycoside hydrolase family 15 in fungi, glycoside hydrolase family 31 of human MGAM, and glycoside hydrolase family 97 of bacterial forms.

Biochem/physiol Actions
α-Amylase is a starch hydrolase, for glucose production, important for energy acquisition. 
Amylases catalyzes the hydrolysis of α-1,4-glycosidic linkages in starch to form glucose, maltose, and maltotriose units. 

In mammals, α-amylase regulates the sugar assimilation by reducing the glucose uptake by Na+/glucose cotransporter 1 (SGLT1) and stimulating glycoprotein N-glycans mediated starch digestion. 
α-Amylase inhibitors are associated with the treatment of type 2 diabetes mellitus. 
α-Amylases are widely known industrial enzymes used in food, detergent, textile, fermentation, and pharmaceutical industries.

Structure
Shown as 1hvx is the structure of the thermostable α-amylase of Bacillus stearothermophilus (BSTA). 
BSTA is comprised of a single polypeptide chain. 
This chain is folded into three domains: A, B and C. 

These domains are generally found on all α-amylase enzymes. 
The A domain constitutes the core structure, with a (β/α)8-barrel.
The B domain consists of a sheet of four anti-parallel β-strands with a pair of anti-parallel β-strands. 
Long loops are observed between the β-strands. 

Located within the B domain is the binding site for Ca2+-Na+-Ca2+. 
Domain C consisting of eight β-strands is assembled into a globular unit forming a Greek key motif. 
Amylases also holds the third Ca2+ binding site in association with domain A. 
Positioned on the C-terminal side of the β-strands of the (β/α)8-barrel in domain A is the active site. 

The catalytic residues involved for the BSTA active site are Asp234, Glu264, and Asp331. 
The residues are identical to other α-amylases, yet there are positional differences which reflect the flexible nature of catalytic resides. 
CaII and CaI with Na found in the interior of domain B and CaIII at the interface of domain A and C, constitute the metal ion binding sites. 

All α-amylases contain one strongly conserved Ca2+ ion for structural integrity and enzymatic activity.
CaI is consistent in α-amylases, however there are structural differences between the linear trio of CaI, CaII and Na in other enzymes. 
CaIII acts as a bridge between two loops, one from α6 of domain A, and one between β1 and β2 of domain C.

Chloride Dependent Enzymes
A family of chloride-dependent enzymes, including salivary and pancreatic α-amylase, require the binding of a chloride ion to be allosterically activated. 
The function of the chloride ion still remains uncertain. 
No relationship has been observed between the anion binding affinity and Amylasess activity, indicating the complexity between the binding parameters and mechanism Amylases activates. 
Studies have shown that nitrite and nitrate ions with pancreatic α-amylase fit within the chloride binding site, thus making all the necessary hydrogen bonds and enhancing the relative activity by 5-fold.

Specificity:

alpha-Amylase catalyzes the hydrolysis of internal alpha-1,4-glucan links in polysaccharides containing 3 or more alpha-1,4-linked D-glucose units, yielding a mixture of maltose and glucose. 
See also Takeshita and Hehre (1975).

Function

Amylases perform the following functions in bakery products:
Provide fermentable and reducing sugars.
Accelerate yeast fermentation and boost gassing for optimum dough expansion during proofing and baking
Intensify flavors and crust color by enhancing Maillard browning and caramelization reactions.

Reduce dough/batter viscosity during starch gelatinization in the oven.
Extend oven rise/spring and improve product volume.
Act as crumb softeners by inhibiting staling.
Modify dough handling properties by reducing stickiness.

Mechanism
In the human body, α-amylase is part of digestion with the breakdown of carbohydrates in the diet. 
The mechanism involved includes catalyzing substrate hydrolysis by a double replacement mechanism, forming a covalent glycosyl-enzyme intermediate and hydrolyzed through oxocarbenium ion-like transition states. 
One of the carboxylic acids in the active site acts as the catalytic nucleophile during the formation of the intermediate. 
A second carboxylic acid operates as the acid/base catalyst, supporting the stabilization of the transition states during the hydrolysis.

Human Salivary and Pancreatic α-Amylase
Salivary α-Amylase hydrolyzes the (α1-4) glycosidic linkages of starch, separating Amylases into short polysaccharide fragments. 
Once the enzyme reaches the stomach, Amylases becomes inactivated due to the acidic pH. 
Further breakdown of starch occurs by secretion of a second form of the enzyme by the pancreas. 

Pancreatic juice enters the duodenum and pancreatic α-amylase further cleaves starch to yield maltose, maltotriose and oligosaccharides. 
The oligosaccharides are referred to as dextrins, which are fragments of amylopectin consisting of (α1-6)branch points. 
Microvilli of the intestinal epithelia break maltose and dextrins into glucose, which gets absorbed into the circulatory system. 
Glycogen has a relatively similar structure as starch, and thus proceeds in the same digestive pathway.

Regulation
α-Amylase is regulated through a number of inhibitors. 
These inhibitors are classified according to six categories, based on their tertiary structures. 
Inhibitors of α-amylase block the active site of the enzyme. 

In animals, inhibitors control the conversion of starch to simple sugars during glucose peaks after a meal so that breakdown of glucose occurs at a rate the body can handle. 
This is particularly important for diabetics, who require low quantities of α-amylase to maintain control over glucose levels. 
After taking insulin however, pancreatic α-amylase escalates. 
Plants use these inhibitors as a defense mechanism to inhibit the use of α-amylase in insects, thus protecting themselves from herbivory.

Physiology
Amylase is a calcium dependent enzyme which hydrolyzes complex carbohydrates at alpha 1,4-linkages to form maltose and glucose. 
Amylase is filtered by renal tubules and resorbed (inactivated) by tubular epithelium. 
Active enzyme does not appear in urine. 
Small amounts of amylase are taken up by Kupffer cells in the liver. 

In healthy dogs, 14% of amylase is bound to globulins. 
Because of this polymerization, canine amylase has variable (high) molecular weights and is not normally filtered by the kidney. 
In dogs with renal disease, this polymerized (macroamylase) amylase is found in higher concentration (from 5-62% of total amylase activity) and contributes to the hyperamylasemia seen in these disorders.

There are four different isoenzymes of amylase in the dog: isoenzyme 3 is found in the pancreas (>50%), whereas isoenzyme 4 is found in all tissues.

Organ specificity:
Pancreas: Found in zymogen granules. 
The pancreas has higher concentrations of amylase than other tissues.
Intestine: Duodenum, ileum
Ovary and testes

Salivary gland: Salivary amylase is found in high concentration in pigs, resulting in high reference intervals for amylase in this species. 
Dogs lack salivary amylase.
Methodology
Amylase assay

There are several different assays for amylase:
Enzymatic
Saccharogenic – This methodology measures the rate of appearance of reducing sugars (glucose, maltose). 
This methodology is invalid in the dog as dog serum contains maltase. 
Maltase is additive to the activity of amylase and will produce increased numbers of reducing sugars.

Amyloclastic – This method measures the hydrolysis of starch and the rate of Amylasess disappearance. 
Valid for dogs and other domestic species. 
Lipemic samples may show an inhibition of enzyme activity which can be overcome by dilution.
Turbidometric: Size of the starch substrate decreases with hydrolysis which reduces light scatter.

Chromogenic substrates: These use dyes bound to synthetic starch substrates, with the dye being released (and measured) once the substrate is hydrolyzed. 
Chromogenic substrate techniques are the current clinical amylase assay.
Reaction type
Enzymatic colorimetric assay

Procedure
α-amylases catalyzes the cleavage of certain oligosaccharides. 
The resulting fragments are completely hydrolyzed to p-nitrophenol and glucose by α-glucosidase. 
The color intensity of the p-nitrophenol is directly proportional to the α-amylase activity.

Application
α-Amylase from hog pancreas has been used:
in the in vitro digestion system to study the hydrolysis of pea globulins
in vitro α-amylase inhibition study
to prepare digestive juice (salivary juice) for the in vitro model of the human digestion system

Uses

Fermentation
α- and β-amylases are important in brewing beer and liquor made from sugars derived from starch. 
In fermentation, yeast ingests sugars and excretes ethanol. 
In beer and some liquors, the sugars present at the beginning of fermentation have been produced by "mashing" grains or other starch sources (such as potatoes). 

In traditional beer brewing, malted barley is mixed with hot water to create a "mash", which is held at a given temperature to allow the amylases in the malted grain to convert the barley's starch into sugars. 
Different temperatures optimize the activity of alpha or beta amylase, resulting in different mixtures of fermentable and unfermentable sugars. 
In selecting mash temperature and grain-to-water ratio, a brewer can change the alcohol content, mouthfeel, aroma, and flavor of the finished beer.

In some historic methods of producing alcoholic beverages, the conversion of starch to sugar starts with the brewer chewing grain to mix Amylases with saliva.
This practice continues to be practiced in home production of some traditional drinks, such as chhaang in the Himalayas, chicha in the Andes and kasiri in Brazil and Suriname.

Flour additive
Amylases are used in breadmaking and to break down complex sugars, such as starch (found in flour), into simple sugars. 
Yeast then feeds on these simple sugars and converts Amylases into the waste products of ethanol and carbon dioxide. 
This imparts flavour and causes the bread to rise. 

While amylases are found naturally in yeast cells, Amylases 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 sourdough. 
Modern breadmaking techniques have included amylases (often in the form of malted barley) into bread improver, thereby making the process faster and more practical for commercial use.

α-Amylase is often listed as an ingredient on commercially package-milled flour. 
Bakers with long exposure to amylase-enriched flour are at risk of developing dermatitis or asthma.

Molecular biology
In molecular biology, the presence of amylase can serve as an additional method of selecting for successful integration of a reporter construct in addition to antibiotic resistance. 
As reporter genes are flanked by homologous regions of the structural gene for amylase, successful integration will disrupt the amylase gene and prevent starch degradation, which is easily detectable through iodine staining.

Uses

Culinary Uses
Amylase is commonly used in bread-making as an additive to improve the conversion of complex sugars into simple sugars that yeast are then able to feed on and produce alcohol and CO2. 
Amylases is also commonly used in beer and liquor production. 
Amylase is often added in the form of malted barley and introduced during the mash phase. 
Similar to the bread-making process, the amylase breaks down the starches into simple sugars allowing the yeast to feed and produce alcohol. 

More generally, amylase could be employed in any situation where starches need to be broken down into simple sugars. 
This can be helpful in uncooked applications where heat may be damaging to fleeting aromas or flavors. 

Medical uses
Amylase also has medical applications in the use of pancreatic enzyme replacement therapy (PERT). 
Amylases is one of the components in Sollpura (liprotamase) to help in the breakdown of saccharides into simple sugars.

Other uses
An inhibitor of alpha-amylase, called phaseolamin, has been tested as a potential diet aid.
When used as a food additive, amylase has E number E1100, and may be derived from pig pancreas or mold fungi.

Bacilliary amylase is also used in clothing and dishwasher detergents to dissolve starches from fabrics and dishes.
Factory workers who work with amylase for any of the above uses are at increased risk of occupational asthma. 
Five to nine percent of bakers have a positive skin test, and a fourth to a third of bakers with breathing problems are hypersensitive to amylase.

Industrial Uses
α-Amylase is used extensively in various industrial processes. 
In textile weaving, starch is added for warping. 
After weaving, the starch is removed by Bacillus subtilis α-amylase. 
Dextrin, which is a viscosity improver, filler, or ingredient of food, is manufactured by the liquefaction of starch by bacteria α-amylase. 

Bacterial α-amylases of B.subtilis, or B.licheniformis are used for the initial starch liquefaction in producing high conversion glucose syrup. 
Pancreatitis can be tested by determining the level of amylases in the blood, a result of damaged amylase-producing cells, or excretion due to renal failure. 
α-Amylase is used for the production of malt, as the enzyme is produced during the germination of cereal grains. 
β/α amylase (BAAM) is a precursor protein which is cleaved to form the β-amylase and α-amylase after secretion.

Hyperamylasemia
Blood serum amylase may be measured for purposes of medical diagnosis. 
A higher than normal concentration may reflect any of several medical conditions, including acute inflammation of the pancreas (Amylases may be measured concurrently with the more specific lipase), perforated peptic ulcer, torsion of an ovarian cyst, strangulation, ileus, mesenteric ischemia, macroamylasemia and mumps. 
Amylase may be measured in other body fluids, including urine and peritoneal fluid.

A January 2007 study from Washington University in St. Louis suggests that saliva tests of the enzyme could be used to indicate sleep deficits, as the enzyme increases Amylasess activity in correlation with the length of time a subject has been deprived of sleep.

History
In 1831, Erhard Friedrich Leuchs (1800–1837) described the hydrolysis of starch by saliva, due to the presence of an enzyme in saliva, "ptyalin", an amylase.
Amylases was named after the Ancient Greek name for saliva: πτύαλον - ptyalon.

The modern history of enzymes began in 1833, when French chemists Anselme Payen and Jean-François Persoz isolated an amylase complex from germinating barley and named Amylases "diastase".
Amylases is from this term that all subsequent enzyme names tend to end in the suffix -ase.
In 1862, Alexander Jakulowitsch Danilewsky (1838–1923) separated pancreatic amylase from trypsin

Etiology and Epidemiology
Although elevated amylase or hyperamylasemia is primarily seen in salivary and pancreatic disease, Amylases may also be seen in different diseases, including gastrointestinal diseases, malignancy, and gynecological diseases. 
Reduced amylase levels can be seen in preeclampsia, cystic fibrosis, and liver disease.

Elevated amylase can be seen in a variety of conditions, including pancreatic disease, salivary disease, decreased metabolic clearance, intestinal disease, and macroamylasemia. 
A chronic increase in amylase may also be seen in a rare condition called Benign Pancreatic Hyperenzymemia or Gullo's syndrome. 
Patients are typically healthy with no pancreatic disease. 
The etiology of the condition is unknown.

Twenty-six (12.5%) of 208 patients with acute abdominal pain unrelated to the pancreas had elevated serum amylase on admission. 
Abnormally elevated amylase levels are seen in 35% of patients with liver disease. 
16-25% of diabetic ketoacidosis cases present with elevated levels of amylase. 
In a group of 74 patients with surgically resectable lung cancer, 13 showed hyperamylasemia.

Pathophysiology
The main function of amylase is to catalyze the hydrolysis of starch into sugars. 
Several isoforms of amylase have been discovered, but the most abundant that exist are pancreatic amylase (P-amylase) and salivary amylase (S-amylase)P-amylase is specifically found in the pancreas and is synthesized by acinar cells then secreted into the gastrointestinal tract. 
S-amylase is primarily produced in salivary glands but can also be produced in ovaries, fallopian tubes, gastrointestinal tract, lungs, striated muscle, and malignant neoplasms. 

Serum amylase is tightly regulated in the body. 
There is a balance between the rate of production and the rate of clearance. 
Elevated amylase may be due to an increase in pancreatic or extrapancreatic production of a decreased rate of clearance.

Amylase has a molecular weight of about 50 to 55 kDa, an optimum physiological pH of 6.7 to 7.0, and requires calcium and chloride ions for optimal enzyme activity.  
The small size allows Amylases to be easily filtered through the glomeruli. 
Amylase is cleared via the kidneys and reticuloendothelial system.

Diagnostic Tests
For many years, amylase has been primarily used for diagnosing acute pancreatitis. 
Amylase can be measured with a blood test or urine test. The urine test may be performed by a clean catch or 24-hour urine collection. The normal range of serum amylase differs from laboratory to laboratory. 
Amylases is clinically important to differentiate pancreatic amylase from other amylase isoforms. 
An elevated amylase with normal lipase may be suggestive of a problem outside the pancreas.

Interfering Factors
Medications, including aspirin, morphine, antiretrovirals, and estrogen-containing medication, can affect serum levels of amylase. 
Macroamylasemia, as referred to above, is another well-recognized cause of elevated serum amylase. 

In this condition, the enzyme forms a complex with proteins such as immunoglobulins and polysaccharides. 
Due to the large size of the macromolecular complex, renal clearance is reduced, causing persistently elevated amylase levels. 
Macroamylasemia can occur in healthy individuals or diseases including autoimmune disease, diabetes, and cancer such as thyroid cancer.

Urinary amylase is typically normal macroamylasemia and can help exclude the condition.  
This condition occurs in 1 percent of healthy individuals and 2.5 percent of individuals with hyperamylasemia. 

Macroamylasemia should be considered in an asymptomatic patient with elevated serum amylase. 
There is no required treatment for the condition. 
Past studies have shown that macroamylasemia was primarily reported in patients with impaired humoral immunity, such as celiac disease, HIV infection, ulcerative colitis, rheumatoid arthritis, and multiple myeloma.

Results, Reporting, Critical Findings
Currently, there is no internationally established reference range for amylase levels. 
The reference range can be as wide as 20-300 U/L. 
However, elevated amylase levels of more than three times the upper limit of normal strongly support the diagnosis of acute pancreatitis. 

Less than this is often associated with other conditions. 
Abnormally low levels of amylase are not common but can be observed in cystic fibrosis, chronic pancreatitis, diabetes mellitus, obesity, and smoking. 
Clinicians should be aware of such causes to help to interpret low amylase activity in patients.

Clinical Significance
Amylase is primarily used in diagnosing pancreatic diseases. 
Amylase is a commonly measured enzyme due to the availability of inexpensive, easily automated methods.
Although amylase is a sensitive indicator of acute pancreatitis, Amylases is not specific as Amylases can be elevated in several conditions unrelated to the pancreas. 

Pancreatitis can be defined by two out of the three following criteria: abdominal pain, serum amylase and/or lipase levels more than three times the upper limit of normal, and abdominal imaging supporting characteristic findings of pancreatitis. 
Therefore, Amylasess clinical significance has been questioned. 
In cases of elevated levels of amylase with little support for pancreatitis, alternative causes of hyperamylasaemia should be considered. 
Amylase is not useful in predicting the severity of an acute pancreatic episode or monitoring the condition. 

Amylase inhibitors such as acarbose have been used in the treatment of type 2 diabetes and have been shown to reduce hemoglobin A1C and peak postprandial glucose. 
Acarbose has also been shown to improve the remission of dumping syndrome in bariatric patients. 
The drug also has also been shown to improve the risk of cardiovascular disease by slowing down the thickening of carotid arteries. 

Elevated amylase can be seen in a wide variety of conditions. 
Amylases is important for clinicians to have a clear, stepwise approach when hyperamylasemia is found. 
This will help avoid unnecessary hospitalization and delayed or inappropriate treatment.

Enhancing Healthcare Team Outcomes
Health care workers must communicate effectively when laboratory results point towards a non-pancreatic cause. 
Amylases is also important to know the different conditions that may affect amylase levels. 
Lipase is typically preferred instead of amylase due to higher specificity. 
Lipase typically stays elevated for up to two weeks, while amylase concentrations remain elevated for up to five days. 

Therefore, amylase is not as clinically useful as lipase if there is a delay between symptom onset and the time the patient seeks medical attention. 
The 2013 American College of Gastroenterology mentions co-ordering lipase and amylase is neither cost-effective nor treatment advantageous. 
Amylases also states that ordering amylase alone is unreliable and does not increase diagnostic efficiency compared to lipase. 
If there is access to lipase testing, adding amylase increases the cost to the patient and has little value in supporting the diagnosis of pancreatitis.

Evolution

Salivary amylase
Saccharides are a food source rich in energy. 
Large polymers such as starch are partially hydrolyzed in the mouth by the enzyme amylase before being cleaved further into sugars. 

Many mammals have seen great expansions in the copy number of the amylase gene. 
These duplications allow for the pancreatic amylase AMY2 to re-target to the salivary glands, allowing animals to detect starch by taste and to digest starch more efficiently and in higher quantities. 
This has happened independently in mice, rats, dogs, pigs, and most importantly, humans after the agricultural revolution.

Following the agricultural revolution 12,000 years ago, human diet began to shift more to plant and animal domestication in place of hunting and gathering. 
Starch has become a staple of the human diet.

Despite the obvious benefits, early humans did not possess salivary amylase, a trend that is also seen in evolutionary relatives of the human, such as chimpanzees and bonobos, who possess either one or no copies of the gene responsible for producing salivary amylase.
Like in other mammals, the pancreatic alpha-amylase AMY2 was duplicated multiple times. 
One event allowed Amylases to evolve salivary specificity, leading to the production of amylase in the saliva (named in humans as AMY1). 
The 1p21.1 region of human chromosome 1 contains many copies of these genes, variously named AMY1A, AMY1B, AMY1C, AMY2A, AMY2B, and so on.

However, not all humans possess the same number of copies of the AMY1 gene. 
Populations known to rely more on saccharides have a higher number of AMY1 copies than human populations that, by comparison, consume little starch. 
The number of AMY1 gene copies in humans can range from six copies in agricultural groups such as European-American and Japanese (two high starch populations) to only two to three copies in hunter-gatherer societies such as the Biaka, Datog, and Yakuts.

The correlation that exists between starch consumption and number of AMY1 copies specific to population suggest that more AMY1 copies in high starch populations has been selected for by natural selection and considered the favorable phenotype for those individuals. 
Therefore, Amylases is most likely that the benefit of an individual possessing more copies of AMY1 in a high starch population increases fitness and produces healthier, fitter offspring.

This fact is especially apparent when comparing geographically close populations with different eating habits that possess a different number of copies of the AMY1 gene. 
Such is the case for some Asian populations that have been shown to possess few AMY1 copies relative to some agricultural populations in Asia. 
This offers strong evidence that natural selection has acted on this gene as opposed to the possibility that the gene has spread through genetic drift.

Variations of amylase copy number in dogs mirrors that of human populations, suggesting they acquired the extra copies as they followed humans around.
Unlike humans whose amylase levels depend on starch content in diet, wild animals eating a broad range of foods tend to have more copies of amylase. 
This may have to do with mainly detection of starch as opposed to digestion.

Product Name: Alpha-Amylase
Source: Human Saliva
Purity: > 90% (SDS-PAGE)
Purity Note: Typically > 98% (SDS-PAGE, two bands at approx. 60kDa)
Form: Lyophilized
Activity: > 100 U/mg (Siemens Dimension® Clinical Chemistry System)
Unit Definition: One unit will catalyze the hydrolysis of one micromole 2-chloro-4-nitrophenyl-a-D-maltotrioside to yield 2-chloro-4-nitrophenol per minute at 37°C.
Protein: > 0.2 mg protein/mg (Coomassie)
Specific Activity: > 400 U/mg protein
Contaminants:
Lipase: < 0.1%
Protease: < 0.1%
Ammonia: < 0.1 micromole/mg
pH: 6.0 - 7.5 (10 mg/mL H2O)
Formulation: Lyophilized from Tris Chloride, Mannitol pH 7.2
Appearance: White to Off-white powder
Solubility: Clear, colorless (10 mg/mL saline)
Storage: -20°C
Recertification: 3 years
Molecular Weight: ~60,000
CAS Number: 9000-90-2
E.C. Number: 3.2.1.1
Gene: AMY1A
Gene ID: 276
Accession No: P04745

Safety Information
Symbol: GHS08
Signal Word: Danger
Hazard Statements: H334
Precautionary Statements: P261, P284, P304+P340, P342+P311, P501

PROPERTIES
Quality Level: 100
biological source: hog pancreas
form: powder
specific activity: ~50 U/mg
storage temp.: 2-8°C

Alpha-amylase

Identifiers
EC no.: 3.2.1.1
CAS no.: 9000-90-2

Beta-amylase

Identifiers
EC no.: 3.2.1.2
CAS no.: 9000-91-3

Gamma-amylase. Glucan 1,4-alpha-glucosidase

Identifiers
EC no.: 3.2.1.3
CAS no.: 9032-08-0

Enzyme Activity: α-Amylase
EC Number: 3.2.1.1
CAZy Family: GH13
CAS Number: 
9000-90-2,
9000-85-5
Source: Bacillus licheniformis
Molecular Weight: 58,000
Expression: Purified from Bacillus licheniformis
Specificity: endo-hydrolysis of α-1,4-D-glucosidic linkages in starch.
Specific Activity: ~ 55 U/mg (40oC, pH 6.5 on Ceralpha reagent)
Unit Definition: One Unit of α-amylase is the amount of enzyme required to release one µmole of p-nitrophenol from blocked p-nitrophenyl-maltoheptaoside per minute (in the presence of excess α-glucosidase) at pH 6.0 and 40oC.
Temperature Optima:    75oC
pH Optima: 6.5
Application examples: For use in Megazyme Dietary Fiber methods.
Method recognition:    EBC Method 6.5

Related words and phrases

adipose
adrenalin
amino acid
amylase
androgen
arnica
beta-carotene
carbohydrase
carbohydrate
cellulose
chlorophyll
chloroplast
citric acid
codon
coenzyme
cryptochrome
denitrification
denitrify
endonuclease
endorphin
enzymatic
enzyme
fatty acid
flavonoid
formic acid
fructose
ghrelin
glycine
glycoprotein
histamine
jute
lanolin
leptin
lycopene
melanin
messenger RNA
mRNA
mycoprotein
nuclease
nucleic acid
nutrient
oestradiol
oestrogen
pepsin
pheromone
phloem
phototropism
plant-derived
polysaccharide
progesterone
protease
protein
resin
resinous
ribonucleic acid
RNA
sap
serotonin
spike protein
steroid
tannin
testosterone
trace element
transfer RNA
triplet codon
tRNA
xylem

Synonyms    
alpha-amylase
4-alpha-D-glucan glucanohydrolase
glycogenase
αamylase# α-amylase
1#4-α-D-glucan glucanohydrolase
EC 3.2.1.1
9001-19-8
endoamylase
Taka-amylase A

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