Search results
Results From The WOW.Com Content Network
In sucrose, the monomers glucose and fructose are linked via an ether bond between C1 on the glucosyl subunit and C2 on the fructosyl unit. The bond is called a glycosidic linkage. Glucose exists predominantly as a mixture of α and β "pyranose" anomers, but sucrose has only the α form.
Glycosidic bonds of the form discussed above are known as O-glycosidic bonds, in reference to the glycosidic oxygen that links the glycoside to the aglycone or reducing end sugar. In analogy, one also considers S-glycosidic bonds (which form thioglycosides ), where the oxygen of the glycosidic bond is replaced with a sulfur atom.
Sucrose, a disaccharide formed from condensation of a molecule of glucose and a molecule of fructose. A disaccharide (also called a double sugar or biose) [1] is the sugar formed when two monosaccharides are joined by glycosidic linkage. [2] Like monosaccharides, disaccharides are simple sugars soluble in water.
Reducing disaccharides like lactose and maltose have only one of their two anomeric carbons involved in the glycosidic bond, while the other is free and can convert to an open-chain form with an aldehyde group. The aldehyde functional group allows the sugar to act as a reducing agent, for example, in the Tollens' test or Benedict's test.
2 O) per bond. [66] Monosaccharides in a closed-chain form can form glycosidic bonds with other monosaccharides, creating disaccharides (such as sucrose) and polysaccharides (such as starch or cellulose). Enzymes must hydrolyze or otherwise break these glycosidic bonds before such compounds become metabolized. After digestion and absorption the ...
Similar to the disaccharides, each glycosidic bond can be formed between any hydroxyl group on the component monosaccharides. Even if all three component sugars are the same (e.g., glucose ), different bond combinations ( regiochemistry ) and stereochemistry (alpha- or beta-) result in trisaccharides that are diastereoisomers with different ...
Enzymes that hydrolyze glycosidic bonds are called "glycoside hydrolases" or "glycosidases". The best-known disaccharide is sucrose (table sugar). Hydrolysis of sucrose yields glucose and fructose. Invertase is a sucrase used industrially for the hydrolysis of sucrose to so-called invert sugar.
Appropriate symbols are used to indicate the stereochemistry of the glycosidic bonds (α or β), the configuration of the monosaccharide residue (D orL), and the substitutions at oxygen atoms (O). [2] Maltose and a derivative of sucrose illustrate these concepts: Maltose