How Does Maltase Work in the Human Body?
Maltase is defined as an enzyme that catalyzes the disaccharide maltose hydrolysis to the simple sugar glucose. This enzyme is present in bacteria, yeast, and plants, and it is thought to be generated by cells of the mucous membrane lining the intestinal wall in humans and other vertebrates.
Maltase
During the digestion process, starch is partially transformed into maltose by salivary or pancreatic enzymes, called amylases; Maltase is secreted by the intestine and then converts maltose into glucose. The body either uses the glucose or stores it as glycogen, also known as animal starch, in the liver.
Intestinal Enzymes
Six intestinal enzymes are needed for starch digestion, two of which are luminal endo-glucosidases, also known as alpha-amylases. The remaining four enzymes have been identified as various maltases, exo-glucosidases bound to the enterocytes' luminal surface. The sucrase-isomaltase system was linked to two of these maltase activities (maltase Ib, maltase Ia). The rest of the two maltases with no distinguishing characteristics were named maltase-glucoamylase (also called maltases II and III). Since they all digest linear starch oligosaccharides to glucose, these four maltases are also known as alpha-glucosidase.
It is similar to alpha-glucosidase in several ways, but the term "maltase" emphasizes the disaccharide nature of the substrate, where the glucose is cleaved, whereas "alpha-glucosidase" emphasizes the bond, whether the substrate is polysaccharide or disaccharide.
Vampire bats are said as the only vertebrates, which are known to not exhibit intestinal maltase activity.
Structure
Maltase is a member of the GH13 (Glycoside hydrolase family 13) of intestinal enzymes that are responsible for transforming complex carbohydrates' - glucosidase linkages into simple glucose molecules for usage. Then, these glucose molecules would be used as a sort of "food" for cells to produce the energy (it means, Adenosine triphosphate) during Cellular respiration. The genes that can code for maltase are given below:
Acid alpha-glucosidase that is coded on the GAA gene is required to break down complex sugars known as Glycogen into glucose.
Maltase-glucoamylase, coded on the MGAM gene, plays a vital role in the digestion of starches. This is because of this enzyme in humans that starches of plant origin are able to digest.
Sucrase-isomaltase, coded on the SI gene, is required for the digestion of carbohydrates, including sucrose, isomaltose, and starch.
Alpha-amylase 1, which is encoded by the AMY1A gene, is responsible for cleaving -glucosidase linkages in polysaccharides and oligosaccharides to generate glycogen and starches, which are then catalyzed by the previous enzymes. This gene's higher quantities in the brain have been represented to lower the risk of Alzheimer's disease.
Mechanism
The hydrolysis of alpha-glucosidase linkage is the mechanism of all Family GH13 enzymes. Maltase focuses on dissolving maltose, which is a disaccharide with a -(1->4) bond connecting two units of glucose. The substrate size determines the rate of hydrolysis (or the carbohydrate size).
Maltase Deficiency
Acid Maltase Deficiency (AMD), also called Pompe disease, was first described in 1932 by a Dutch pathologist named JC Pompe. AMD is given as a non-sex-linked autosomal recessive condition, where the excessive accumulation of glycogen builds up within the lysosome vacuoles in nearly all types of cells and all over the body. It is the most serious glycogen storage disease that affects muscle tissue.
AMD is also categorized into three separate types according to the age of onset of the symptoms in affected individuals. Infantile (which is Type a), childhood (which is Type b), and adulthood (which is Type c). The AMD type is defined by the gene mutation type, which was localized in 17q23. At the same time, the mutation type will determine the production level of acid maltase. AMD is fatal, and type-a generally dies of heart failure before age one. Type-b die of respiratory failure between 3-24 ages. And, type-c die of respiratory failure at the age of 10-20 of the onset of symptoms.
Production of Maltase Enzyme
Starch is partially transformed into maltose during the digestion process by the salivary or pancreatic enzymes known as amylases (amylase maltase); maltase is secreted by the intestine and then converts maltose into glucose. The so-produced glucose is either utilized by the body or can be stored in the liver as glycogen (or called animal starch).
Industrial Applications
Alpha-amylase contains an essential function in the degradation of starches, so it is extremely and commonly used in the baking industry of baking. Also, it is mostly used as a means of flavor, enhancing it to improve bread quality. With no alpha-amylase, the yeast would not be possible to ferment.
Commonly, maltose-glucoamylase can be used as a fermentation source as it is capable of cutting starch into maltose that can then be used for brewing sake and beers.
Maltose glucoamylase has been studied outside of brewing by adding complex inhibitors to avoid the hydrolysis of alpha-glucosidase linkages. By inhibiting the linkage cleave, scientists are hoping to devise a drug that is less toxic and more efficient to treat diabetes.
Amino Acids in Maltase
We have learned already that maltase is a very important part of our body mechanism and plays a vital role in it. We have also seen what deficiency of maltase can cause and how it helps in the process of conversion of maltose into glucose. Now let’s understand which amino acids are present in maltase. Studies have shown that tryptophan, histidine, and cysteine are required for both maltase and glucoamylase activities in the kidney enzyme, whereas tryptophan, histidine, and lysine were required for maltase and glucoamylase activities in the intestine enzyme.
Maltase Use in Yeast and its Mechanism
Maltase is a part of our daily life but also it has many daily life applications one of which is bread. Interestingly, the enzyme maltase, which converts maltose to glucose, is present in the yeast which is used in bread-making. Now let’s understand the mechanism of how maltase helps yeast in the making of bread. A maltose molecule is first absorbed by the yeast cell and maltase then binds it to maltose, splitting it into two or half. Invertase, like sucrose, is a sucrose-breaking enzyme that is also found in yeast cells. This enzyme works on the flour's small amount of sucrose. These two enzymes invertase and maltase which are responsible for creating a large portion of the glucose required for yeast to ferment and form the final product which is bread.
Effect of pH on Enzymes
In chemistry pH is a key term that is commonly heard either it’s experimenting in labs or going through theories, similarly the pH is also connected to enzymes as enzymes are also affected by the changes in the pH level. Many things can be scaled on the basis of pH in chemistry, similarly determining what will be the right pH helps a lot in the case of enzymes too. In this case, the most favorable pH value helps in determining the point at which the enzyme is most active and this point is also known as the optimum pH.
The extreme level of high or low pH values sometimes results in a complete loss of activity in most of the enzymes. pH is also a key factor in maintaining the stability of enzymes. As with the activity, for each of the enzymes, there is also a region of pH optimal stability.
Enzymes their Substrates and the End-products
There are many other enzymes along with maltase that play a vital role in the digestion process in the human body as well as in other processes but in which they form their substrate and an end product. Let's have a look at a few enzymes including maltase with their substrate and end products.
Maltase- The substrate of maltase is maltose which when carried further in the process gives glucose as the final product or end product.
Protease- Protease is an enzyme that is produced in the stomach and pancreas. The substrate of protease is protein and the end product is amino acids.
Lipase- Lipase is produced in the pancreas; its substrate is lipids which in simple language can also be said as fats and oils for the main end product which are fatty acids and glycerol.
Pancreatic amylase- The substrate of pancreatic amylase is starch which finally forms maltose as its final product and is also produced in the pancreas.
Salivary amylase- Salivary amylase is produced in the salivary glands as can be understood by the name itself; its substrate is starch and the end product is maltose.
FAQs on Maltase Enzyme: Key to Carbohydrate Digestion
1. What is the maltase enzyme and what is its primary function in the human body?
Maltase is a type of enzyme known as a glycoside hydrolase. Its primary function is to catalyse the final step in carbohydrate digestion by breaking down the disaccharide maltose into two simpler, absorbable units of the monosaccharide glucose. This process is essential for providing the body with its main source of energy.
2. Where is the maltase enzyme produced and found in the digestive system?
The maltase enzyme is produced by the cells lining the walls of the small intestine, known as enterocytes. It is located on the brush border (microvilli) of these intestinal cells, which is the site where the final digestion and absorption of carbohydrates occur.
3. What is the specific substrate for maltase, and what are the products of the reaction it catalyses?
The specific substrate for the maltase enzyme is maltose, a disaccharide sugar. Through a hydrolysis reaction, maltase breaks one molecule of maltose down into two molecules of glucose, which is a monosaccharide. This can be represented by the chemical equation: C₁₂H₂₂O₁₁ (Maltose) + H₂O → 2C₆H₁₂O₆ (Glucose).
4. What type of biomolecule is maltase, and how is it classified as an enzyme?
Maltase is a protein that functions as a biological catalyst. As an enzyme, it is classified as a hydrolase. This is because it uses a water molecule (hydrolysis) to break the glycosidic bond that holds the maltose molecule together, separating it into its constituent glucose units.
5. How do the enzymes amylase and maltase work together in a sequence to completely digest starch?
The digestion of starch is a two-step process involving both amylase and maltase. First, amylase (found in saliva and secreted by the pancreas) begins the breakdown of large starch polysaccharides into smaller disaccharide units of maltose. Then, as these maltose molecules reach the small intestine, maltase, located on the intestinal wall, completes the process by breaking each maltose molecule into two glucose molecules, which are then absorbed into the bloodstream.
6. What are the physiological consequences if the body cannot produce enough maltase?
A deficiency in maltase production leads to a condition called maltose intolerance. Without sufficient maltase, ingested maltose cannot be broken down and absorbed in the small intestine. It then travels to the large intestine, where it is fermented by gut bacteria. This fermentation process can lead to several uncomfortable symptoms, including:
Bloating and abdominal cramps
Excessive gas (flatulence)
Diarrhoea
7. Why is the breakdown of maltose into glucose so important for the body's energy supply?
The breakdown is crucial because glucose is the body's primary and most readily usable source of energy. Cells throughout the body, especially the brain, rely on glucose for cellular respiration to produce ATP (adenosine triphosphate), the main energy currency of the cell. Maltose is a complex sugar that is too large to be absorbed by the intestinal walls and used by cells directly. Maltase performs the essential final step of converting it into the simple, absorbable fuel that powers all bodily functions.
8. How does the pH level of the digestive tract affect the activity of the maltase enzyme?
Like all enzymes, maltase has an optimal pH at which it functions most efficiently. It is adapted to work in the slightly alkaline environment of the small intestine, which typically has a pH between 7.0 and 8.5. If the environment becomes too acidic (like the stomach's pH of 1.5-3.5) or excessively alkaline, the enzyme's three-dimensional protein structure can denature. This change alters the shape of its active site, preventing it from binding to its substrate (maltose) and drastically reducing its digestive capability.
