Disaccharides


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Disaccharides

 

bioses, carbohydrates whose molecules consist of two monosaccharide groups. All disaccharides have a glycoside type of structure in which the hydrogen atom of a glycoside hydroxyl of one monosaccharide molecule is replaced by a group from another monosaccharide molecule bonded by a hemiacetal or alcohol hydroxyl. In the former case the disaccharides that form lack reducing properties, but in the second case they have them (I). The group of irreducible disaccharides includes trehalose (mycose, or fungus sugar), which consists of two glucose groups (II), and saccharose, which consists of glucose and fructose groups (III). The group of reducible disaccharides includes maltose (IV), cellobiose (V), and lactose (VI).

Disaccharides may contain the five- or six-membered rings of the monosaccharides (pentoses and hexoses) and may differ with respect to the configuration of the glycoside bond (α- or β-glycosides). The spatial forms (conformations) of the rings of the monosaccharide groups in the various disaccharides can vary. Thus, cellobiose and maltose differ not only in the configuration of the glycoside bond (α in maltose and β in cellobiose) but also in the fact that in cellobiose both groups have the same conformation, whereas in maltose they are different.

Disaccharides crystallize well, are readily soluble in water and 45-48-percent alcohol, only slightly soluble in 96-percent alcohol, optically active, and sweet to the taste. They are hydrolyzed by acids (in the case of saccharose it is called inversion); if the monosaccharide group has a five-membered ring the rate of acid hydrolysis of the disaccharide is increased. Disaccharides are also hydrolyzed by enzymes (carbohydrases), such as α- and β-glucosidases (depending on the type of glycoside bond in the disaccharide). Hydrolysis produces monosaccharides.

Disaccharides are widespread in animals and plants. They occur in the free state (as products of biosynthesis or of partial hydrolysis of polysaccharides) and in the form of structural components of glycosides and other compounds. Disaccharides are usually produced from natural sources— for example, saccharose from the sugar beet or from sugar-cane, and lactose from milk. Many disaccharides can be synthesized by chemical and biochemical means.

Saccharose, lactose, and maltose are valuable food and flavoring substances. The sugar industry produces saccharose.

REFERENCES

Khimiia uglevodov. Moscow, 1967.
Stepanenko, B. N. Uglevody: Uspekhi v izuchenii stroeniia i metabolizma. Moscow, 1968.
Stanèk, J., J. Černý, and J. Pacák. The Oligosaccharides. Prague, 1965.

B. N. STEPANENKO

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The sensory attributes of all samples prepared with the three disaccharides were measured in triplicate.
Non-absorbable disaccharides versus placebo/ no intervention and lactulose versus lactitol for the prevention and treatment of hepatic encephalopathy in people with cirrhosis.
Divergent synthesis of chondroitin sulfate disaccharides and identification of sulfate motifs that inhibit triple negative breast cancer.
In fact, when melibiose, which is a disaccharide having an acid-labile 1,6-glycosidic bond, was treated with methanol in the presence of hydrogen chloride under Fischer's conditions, the product was a mixture of monosaccharide derivatives as a result of glycosidic bond cleavage.
Also, the determination of disaccharides in the sieved and residual flour recorded significant decrease in the disaccharides of sieved and residual flour respectively was 15.
There are also changes in how the sample is dried in order to prevent water weight from affecting the test results, plus a test to verify the activity level of the enzymes used to digest the chondroitin into its component disaccharides (a potential issue because different suppliers might produce enzymes with different activity levels).
Previous studies determined that the honeydew produced by aphids contained a mixture of monosaccharides, disaccharides, and trisaccharides (Volkl et al.
Fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) such as apples, beans, white bread, and milk are poorly absorbed in the small intestine, which can trigger bouts of gas from colonic bacterial fermentation and diarrhea because of osmotic water transfer into the lumen of the colon.
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Free sugar generally comprises of monosaccharides (like glucose or fructose)/ disaccharides (like sucrose) added to foods and drinks, and natural sugar present in honey, fruit juices, etc [4].
The detailed investigation of carbohydrates was carried out that resulted in the identification of reducing sugars, polysaccharides, disaccharides and monosaccharides including glucose.
Tomatsu and coworkers studied the enzymatic degradation of glycosaminoglycans in DBS and measured a disaccharide derived from chondroitin sulfate, and 2 disaccharides derived from heparan sulfate (65).