Maltase: Enzyme, Structure & Mechanism

Maltase is an enzyme that catalyzes the conversion of maltose, a disaccharide, to glucose, a simple sugar. The enzyme is present in yeast, plants, and bacteria and is considered to be produced by cells of the mucous membrane in the lining of the intestinal wall in humans and other vertebrates. During digestion, pancreatic or salivary enzymes called amylases convert starch to maltose, which is then converted to glucose by maltase released by the colon. The glucose produced is either used by the organism or stored as glycogen in the liver (animal starch).

Key Terms: Maltase, Enzymes, Maltose, Amino Acids, Glucose, Pancreatic Enzyme, Yeast, Acid, Alpha-Glucosidase

---

Maltase

[Click Here for Sample Questions]

For the digestion of starch, six digestive enzymes are required. Two of these enzymes are alpha-amylases, which are luminal endo-glucosidases. The remaining 4 enzymes are various maltases, exo-glucosidases linked to the luminal membrane of enterocytes. Sucrase-isomaltase was linked to two of these maltase activities (maltase Ib, maltase Ia). Maltase-glucoamylase was the name given to the other two maltases that had no differentiating properties (maltases II and III). As they all digest linear starch oligosaccharides to glucose, these four maltases are also known as alpha-glucosidase.

Maltose to Glucose

---

Structure of Maltase

[Click Here for Sample Questions]

Maltase belongs to the Family GH13 (Glycoside hydrolase family 13) of intestinal enzymes that are responsible for breaking down the -glucosidase connections of complex carbohydrates into simple glucose molecules to make use of them. Cells would then utilise the glucose molecules as "food" to make energy (Adenosine triphosphate) during cellular respiration. Maltase can be coded for by the genes as below:

• The GAA gene coded for acid alpha-glucosidase is required for the breakdown of complex sugars, glycogen into glucose.
• Maltase-glucoamylase, encoded by the MGAM gene, is involved in starch digestion. Starches of plant origin can be digested in humans due to this enzyme.
• Sucrase-isomaltase that is coded on the SI gene is required for the digestion of carbohydrates such as starch, sucrose, and isomaltose.
• Alpha-amylase 1, encoded by the AMY1A gene is responsible for cleaving -glucosidase links in oligosaccharides and polysaccharides to produce starches and glycogen for the previous enzymes to catalyse. The presence of this gene in the brain in higher quantities has been linked to a lower risk of Alzheimer's disease.

Structure of Maltase

---

Mechanism of Maltase

[Click Here for Sample Questions]

The mechanism of all Family GH13 enzymes is to hydrolyze -glucosidase bond and hence break it. Maltase targets α-(1->4) bond in maltose, a disaccharide that serves as a connection between two units of glucose. The size of the substrate (carbohydrate size) determines the rate of hydrolysis.

---

Maltase Deficiency

[Click Here for Sample Questions]

Pompes disease, commonly known as Acid Maltase Deficiency (AMD), is a genetically inherited condition that affects muscle function. Patients with AMD have a deficiency, or mutation, in the Acid Alpha-Glucosidase (GAA) gene, which controls muscle function. Patients with AMD have a chemical called glycogen build up in their muscles as a result of this genetic abnormality. Glycogen is a type of carbohydrate that is utilised to store energy in the short term. Glycogen build-up in the muscles of people with AMD promotes muscle degeneration, which leads to increased muscle weakness. The heart and respiratory muscles may be weakened as a result of this glycogen build-up.

The most common cause of mortality in AMD patients is cardiac or respiratory failure. One in every 40,000 to 100,000 babies is thought to be affected by AMD. The start of AMD varies from patient to patient, and it might strike newborns, children, or adults. The most severe form is newborn onset, which usually results in mortality within a year.

In general, the later AMD appears, the slower it progresses and the less severe the symptoms become. When children and adults are diagnosed with AMD, their life expectancy ranges from 10 to 20 years after symptoms develop.

---

Production of Maltase Enzyme

[Click Here for Sample Questions]

During digestion, salivary or pancreatic enzymes known as amylases (amylase maltase) partially convert starch to maltose; maltase is released by the colon and then transforms maltose to glucose. The glucose produced is either used by the organism or stored as glycogen in the liver (or called animal starch).

---

Industrial Applications

[Click Here for Sample Questions]

As alpha-amylase plays a crucial role in the breakdown of starches, it is widely employed in the baking business. It is generally used as a taste enhancer to improve the quality of bread. Yeast would be unable to ferment without alpha-amylase. Maltose-glucoamylase is a typical fermentation source because it can break down starch into maltose, which may then be utilised to brew beers and sake. Maltose glucoamylase has been explored outside of brewing by adding particular inhibitors that prevent the hydrolysis of the -glucosidase links.

---

Difference between Maltose and Maltase

[Click Here for Sample Questions]

Maltose is a carbohydrate that is generated when amylase digests starch and is transformed to glucose by maltase. It is also an isomer of trehalose. Maltase is a maltose-to-glucose hydrolase enzyme that is frequently confused with amylase.

• Maltose, also known as maltobiose and malt sugar, is a crystalline disaccharide (C₁₂H₂₂O₁₁) produced from starch by the action of malt diastase and the amylolytic ferment of saliva and pancreatic juice. Its chemical formula is 4-O-. It's white crystalline sugar that forms when carbs are digested.
• Maltase is an enzyme that catalyses the breakdown of maltose and other carbohydrates into glucose and is found in saliva and pancreatic juice.

Maltase

---

Amino Acids in Maltase

[Click Here for Sample Questions]

The following amino acids are found in maltase:

• Alanine
• Arginine
• Aspartic Acid
• Glutamic Acid
• Glycine
• Isoleucine
• Leucine
• Lysine
• Methionine
• Phenylalanine
• Proline
• Serine
• Threonine
• Tyrosine
• Valine

---

Maltase Use in Yeast and its Mechanism

[Click Here for Sample Questions]

The enzyme maltase, which converts maltose to glucose, is found in the yeast used in bread production. 

• A maltose molecule is initially taken by the yeast cell, after which maltase binds to it and splits it in half. 
• Invertase is a sucrose-breaking enzyme found in yeast cells, just like sucrose. 
• This enzyme breaks down the little quantity of sugar in flour. 
• Invertase and maltase are two enzymes that are responsible for producing a major amount of the glucose required for yeast to ferment and make the final product, bread.

---

Things to Remember

[Click Here for Sample Questions]

• Maltase is an alpha-glucosidase enzyme that breaks down disaccharides like maltose into individual glucose molecules.
• Pompes disease, also known as Acid Maltase Deficiency (AMD), is a genetically inherited muscle-function disorder. 
• The Acid Alpha-Glucosidase (GAA) gene, which governs muscle function, is deficient or mutated in AMD patients.
• Maltose, also known as maltobiose and malt sugar, is a crystalline disaccharide (C₁₂H₂₂O₁₁) produced from starch by malt diastase and the amylolytic fermentation of saliva and pancreatic juice.
• Maltase is a member of the GH13 (Glycoside hydrolase family 13) of intestinal enzymes that break down the -glucosidase linkages of complicated carbohydrates into easy-to-use glucose molecules.

---