Sucrase-isomaltase: Difference between revisions

Latest revision as of 11:05, 15 February 2025

Sucrase-Isomaltase[edit]

Sucrase-isomaltase is an important enzyme complex located in the small intestine that plays a crucial role in the digestion of carbohydrates. It is responsible for the hydrolysis of sucrose and isomaltose, breaking them down into simpler sugars that can be absorbed by the body.

Structure[edit]

Sucrase-isomaltase is a glycoprotein composed of two subunits: sucrase and isomaltase. These subunits are linked together and anchored to the brush border membrane of the intestinal epithelial cells. The enzyme complex is synthesized as a single polypeptide chain that is later cleaved into the two functional subunits.

Function[edit]

The primary function of sucrase-isomaltase is to catalyze the breakdown of disaccharides into monosaccharides. Sucrase specifically hydrolyzes sucrose into glucose and fructose, while isomaltase breaks down isomaltose and other alpha-limit dextrins into glucose. This enzymatic activity is essential for the proper digestion and absorption of dietary carbohydrates.

Clinical Significance[edit]

Deficiency in sucrase-isomaltase activity can lead to a condition known as sucrase-isomaltase deficiency, which results in the malabsorption of sucrose and isomaltose. This can cause symptoms such as diarrhea, abdominal pain, and bloating after the ingestion of sucrose-containing foods. Diagnosis is typically made through a combination of clinical evaluation, dietary history, and enzymatic assays.

Related Pages[edit]

@@ Line 1: / Line 1: @@
-'''Sucrase-isomaltase''' is a [[glycoprotein]] enzyme complex located in the [[brush border]] of the [[small intestine]]. It plays a crucial role in the digestion of [[dietary sugars]], specifically [[sucrose]] (table sugar) and [[isomaltose]], a type of [[maltose]]. This enzyme complex is composed of two subunits: sucrase, which catalyzes the hydrolysis of sucrose to [[glucose]] and [[fructose]], and isomaltase, which breaks down isomaltose and other [[alpha-limit dextrins]] into glucose. The proper functioning of sucrase-isomaltase is essential for the efficient absorption of digested sugars into the bloodstream.
+== Sucrase-Isomaltase ==
-==Structure and Function==
+[[File:SI_active_site.png|thumb|right|300px|Active site of sucrase-isomaltase.]]
-Sucrase-isomaltase is anchored to the membrane of the intestinal epithelial cells by a single transmembrane domain. The enzyme is synthesized in the [[endoplasmic reticulum]] and transported to the [[Golgi apparatus]] for further processing and maturation before being delivered to the brush border membrane. The complex is a type II membrane protein, meaning its N-terminus is located inside the cell, and the C-terminus faces the intestinal lumen.
-The sucrase subunit preferentially hydrolyzes sucrose, producing equal amounts of glucose and fructose, which are then absorbed by the enterocytes. The isomaltase subunit, on the other hand, targets alpha-1,6 glycosidic bonds found in isomaltose, maltose, and other oligosaccharides, releasing glucose.
+'''Sucrase-isomaltase''' is an important [[enzyme]] complex located in the [[small intestine]] that plays a crucial role in the digestion of [[carbohydrates]]. It is responsible for the hydrolysis of [[sucrose]] and [[isomaltose]], breaking them down into simpler sugars that can be absorbed by the body.
-==Clinical Significance==
+== Structure ==
-Deficiencies in sucrase-isomaltase activity can lead to [[congenital sucrase-isomaltase deficiency]] (CSID), a rare disorder characterized by the malabsorption of sucrose and isomaltose. Individuals with CSID experience symptoms such as bloating, abdominal pain, diarrhea, and gas when consuming foods containing sucrose and maltose. Diagnosis is typically made through a combination of clinical evaluation, breath testing, and intestinal biopsy. Management of CSID involves dietary modifications to limit the intake of problematic sugars.
-In addition to CSID, variations in the gene encoding sucrase-isomaltase have been associated with an increased risk of developing [[irritable bowel syndrome]] (IBS), particularly in populations with specific dietary habits that include high intake of sucrose and isomaltose.
+Sucrase-isomaltase is a [[glycoprotein]] composed of two subunits: sucrase and isomaltase. These subunits are linked together and anchored to the [[brush border]] membrane of the intestinal epithelial cells. The enzyme complex is synthesized as a single polypeptide chain that is later cleaved into the two functional subunits.
-==Genetics==
+== Function ==
-The gene encoding the sucrase-isomaltase enzyme complex is located on chromosome 3q26. The gene undergoes complex [[alternative splicing]], resulting in multiple isoforms of the enzyme, which may have implications for the regulation of carbohydrate digestion and absorption.
-==Research Directions==
+The primary function of sucrase-isomaltase is to catalyze the breakdown of disaccharides into monosaccharides. Sucrase specifically hydrolyzes sucrose into [[glucose]] and [[fructose]], while isomaltase breaks down isomaltose and other [[alpha-limit dextrins]] into glucose. This enzymatic activity is essential for the proper digestion and absorption of dietary carbohydrates.
-Recent studies have focused on understanding the molecular mechanisms underlying the regulation of sucrase-isomaltase expression and activity in response to dietary changes. There is also interest in developing therapeutic strategies for CSID, including enzyme replacement therapy and gene therapy. Additionally, research into the role of sucrase-isomaltase in health and disease extends beyond CSID, exploring its potential involvement in metabolic disorders such as [[obesity]] and [[diabetes mellitus]].
+== Clinical Significance ==
+Deficiency in sucrase-isomaltase activity can lead to a condition known as [[sucrase-isomaltase deficiency]], which results in the malabsorption of sucrose and isomaltose. This can cause symptoms such as [[diarrhea]], [[abdominal pain]], and [[bloating]] after the ingestion of sucrose-containing foods. Diagnosis is typically made through a combination of clinical evaluation, dietary history, and enzymatic assays.
+== Related Pages ==
+* [[Carbohydrate digestion]]
+* [[Enzyme]]
+* [[Small intestine]]
+* [[Glycoprotein]]
+[[Category:Enzymes]]
 [[Category:Digestive system]]
-[[Category:Enzymes]]
-[[Category:Human proteins]]
-{{Medicine-stub}}