- Cellobiose
- cellulose
- dehydration reaction
- diastereoisomer
- fructose
- galactose
- Gentiobiose
- Gentiobiulose
- glucose
- glycosidic bond
- hemiacetal
- hydrolysis
- Isomaltose
- Kojibiose
- lactose
- Lactulose
- Laminaribiose
- maltose
- Maltulose
- Mannobiose
- mannose
- Melibiose
- Melibiulose
- monomer
- monomers
- monosaccharide
- monosaccharides
- Nigerose
- oligosaccharide
- Palatinose
- polysaccharide
- Polysaccharides
- rhamnose
- Rutinose
- Rutinulose
- Sophorose
- starch
- Sucrose
- sugar
- trehalose
- Trisaccharide
- Turanose
- Xylobiose
- xylopyranose

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'Disaccharide' is one of the four chemical groupings of carbohydrates (monosaccharide, disaccharide, oligosaccharide, and polysaccharide).
Classification
There are two different types of disaccharides: reducing disaccharides, in which one monosaccharide, the reducing sugar, still has a free hemiacetal unit; and non-reducing disaccharides, in which the components bond through an acetal linkage between their anomeric centers and neither monosaccharide has a free hemiacetal unit. Cellobiose and maltose are examples of reducing disaccharides. Sucrose and trehalose are examples of non-reducing disaccharides.
Formation
Disaccharides are formed when two monosaccharides are joined together and a molecule of water is removed. For example; milk sugar (lactose) is made from glucose and galactose whereas the sugar from sugar cane and sugar beets (sucrose) is made from glucose and fructose.The two monosaccharides are bonded via a dehydration reaction (also called a condensation reaction or dehydration synthesis) that leads to the loss of a molecule of water and formation of a glycosidic bond.
Properties
The glycosidic bond can be formed between any hydroxyl group on the component monosaccharide. So, even if both component sugars are the same (e.g., glucose), different bond combinations (regiochemistry) and stereochemistry (alpha- or beta-) result in disaccharides that are diastereoisomers with different chemical and physical properties.Depending on the monosaccharide constituents, disaccharides are sometimes crystalline, sometimes water-soluble, and sometimes sweet-tasting and sticky-feeling.
Common disaccharides
Disaccharide | Unit 1| | Unit 2 | Bond |
Sucrose (table sugar, cane sugar, beet sugar, or saccharose) || | glucose | fructose | α(1→2)β |
Lactulose || | galactose | fructose | β(1→4) |
Lactose (milk sugar) || | galactose | glucose | β(1→4) |
Maltose || | glucose | glucose | α(1→4) |
Trehalose || | glucose | glucose | α(1→1)α |
Cellobiose || | glucose | glucose | β(1→4) |
Maltose and cellobiose are hydrolysis products of the polysaccharides, starch and cellulose, respectively.
Less common disaccharides include:
Disaccharide | Units | ||
Kojibiose || | two glucose monomers | α(1→2) < | |
| | two glucose monomers | α(1→3) | |
Isomaltose || | two glucose monomers | α(1→6) | |
β,β-Trehalose || | two glucose monomers | β(1→1)β | |
α,β-Trehalose || | two glucose monomers | α(1→1)β< | |
| | two glucose monomers | β(1→2) | |
Laminaribiose || | two glucose monomers | β(1→3) | |
Gentiobiose || | two glucose monomers | β(1→6) | |
Turanose || | a glucose monomer and a fructose monomer | α(1→3) | |
Maltulose || | a glucose monomer and a fructose monomer | α(1→4) | |
Palatinose || | a glucose monomer and a fructose monomer | α(1→6) | |
Gentiobiulose || | a glucose monomer and a fructose monomer | β(1→6) | |
Mannobiose || | two mannose monomers | either α(1→2), α(1→3), α(1→4), or α(1→6) | |
Melibiose || | a galactose monomer and a glucose monomer | α(1→6) | |
Melibiulose || | a galactose monomer and a fructose monomer | α(1→6) | |
Rutinose || | a rhamnose monomer and a glucose monomer | α(1→6) | |
Rutinulose || | a rhamnose monomer and a fructose monomer | β(1→6) | |
Xylobiose || | two xylopyranose monomers | β(1→4) |
See also
References
External links
Category:Carbohydrate chemistry *
ar:سكر ثنائي be:Дыцукрыды bs:Disaharidi bg:Дизахарид ca:Disacàrid cs:Disacharidy de:Disaccharide et:Disahhariidid el:Δισακχαρίτης es:Disacárido eo:Disakarido eu:Disakarido fa:دیساکارید fr:Diholoside fy:Disacharide gl:Disacárido ko:이당류 is:Tvísykrur it:Disaccaride he:דו-סוכר kk:Дисахаридтер la:Disaccharides lt:Disacharidai mk:Дисахарид ms:Disakarida nl:Disacharide ja:二糖 no:Disakkarid oc:Disacarid pl:Disacharydy pt:Dissacarídeo ru:Дисахариды sq:Disakaridet simple:Disaccharide sk:Disacharid fi:Disakkaridi sv:Disackarid ta:இரட்டைச்சர்க்கரை th:ไดแซ็กคาไรด์ uk:Дисахариди vi:Disacarit zh-yue:二糖 zh:雙醣This text is licensed under the Creative Commons CC-BY-SA License. This text was originally published on Wikipedia and was developed by the Wikipedia community.