Disaccharides and Oligosaccharides

The word “Saccharide” translates to sugar, for example, glucose, fructose or galactose, or other carbohydrates. Simple carbohydrates consist of two groups, Monosaccharides, and Disaccharides. Monosaccharides cannot be broken down into simple units of sugar as they already consist of glucose, fructose, or galactose (simple sugar unit). The combination of these three monosaccharides in various ways forms more complex carbohydrates. Disaccharides are often defined as two monosaccharides joined together with the help of a glycoside bond. Complex Carbohydrates have three or more monosaccharide bond, Oligosaccharides falls under the group of carbohydrates that have a few sugars, around 3 – 15, joined together with the help of a glycoside bond. Thus Disaccharides and Oligosaccharides are simple and complex forms of carbohydrates.

Disaccharides and their examples

Disaccharides are crystalline water-soluble compounds, they are also known as “double sugar,” as they contain two molecules of simple sugar linked together, this takes place through dehydration reaction and a water molecule is removed for each linkage. There are a variety of combinations of bonds and stereochemistry which helps in the production of Disaccharides with uniqueness in their properties. Disaccharides can be both natural as well as artificial. 

Examples-

Some of the Disaccharides examples are listed below-

• Lactose 

Galactose + glucose

They are mostly found in milk and it is also a sucrose isomer. Formula for Lactose is C12H22O11

• Sucrose

Glucose + fructose

They are natural Disaccharides, purified and produced by sugar cane. Sucrose is one of the important Disaccharide examples.

• Maltose

Glucose + glucose

It is often known as malt sugar or maltobiose and has a density of 1054g/cm3 and appears like crystal or white powder. It can be obtained by purifying barley and other grains and is a product of starch digestion.  

• Lactulose

Galactose + fructose

It is a man-made or synthetic, non-absorbable sugar, but helps in softening the stool by absorption of water with the help of the colon that is broken down into products. Lactulose has a molar mass og 342.297 g.mol-1.

• Cellobiose 

Glucose + glucose 

Cellobiose is formed where cellulose is digested like in cellulolytic bacteria. It is generally created by joining two beta-glucose molecules by a β(1 4) bond. It is a hydrolysis product of cellulose-rich materials like cotton or paper.

• Trehalose

Glucose + glucose

It appears as white orthorhombic crystals and is often known as tremalose or mycose. Trehalose has high water retention properties and also is a natural Disaccharide. 

What are oligosaccharides? 

The answer to the question “What are Oligosaccharides?” is super simple, Oligosaccharides represents the combination of 3 – 10 Monosaccharide, they are usually not the free-floating sugar in the body. It has several functions like cell binding and cell recognition. Many times the human digestive system is unable to break down the carbohydrates, thus the Oligosaccharides acts as prebiotics, which is the food source for healthy bacteria in the guts.

Examples- 

• Trisaccharides

Trisaccharides are a type of Oligosaccharide consisting of three Monosaccharides along with two glycosidic bonds joining them. Some of the examples are-

1. Nigerotriose, 3 units of glucose linked by a(1             3) glycosidic linkage
2. Maltotriose, 3 units of glucose linked by a(1            4) glycosidic linkage
3. Maltotriulose glucose – glucose-fructose linked by a(1  4) glycosidic linkage

• Tetrasaccharides

Tetrasaccharides are a type of Oligosaccharide consisting of four Monosaccharides. The formula for Tetrasaccharides is C24H42O21. Some of the examples are-

1. Nigerotetraose, 4 units of  glucose linked by a(1      3) glycosidic linkage  
2. Maltotetraose, 4 units of glucose linked by a(1     4) glycosidic linkage
3. Stachyose consist of galactose- galactose-glucose-fructose
4. Nystose, consist of glucose–fructose-fructose-fructose

• Pentasaccharides

Pentasaccharides are a type of Oligosaccharide consisting of five Monosaccharides. One of the examples of Pentasaccharide is Verbascose, which consists of galactose- galactose- galactose-glucose-fructose.

• Hexasaccharides

Hexasaccharides are a type of Oligosaccharide consisting of six Monosaccharides. One of its examples is Alpha-Cyclodextrin, the formula for which is C36H60O30

• Heptasaccharides

The word “hepta” denotes the number seven, thus Heptasaccharides are a type of Oligosaccharide consisting of seven Monosaccharides.

• Octasaccharides

Octasaccharides are a type of Oligosaccharide consisting of eight Monosaccharides.

• Nonasacchardies

Nonasacchardies are a type of Oligosaccharide that consists of nine molecules of sugar or Monosaccharides.

• Decasacchardies 

The word “deca” usually denotes the number ten, thus Decasacchardies are a type of Oligosaccharide that consists of ten molecules of sugar or Monosaccharides.

Conclusion

To conclude everything that is mentioned in the article disaccharides and oligosaccharides is carbohydrates, which serves completely different functions and have unique molecular structure. Disaccharides and oligosaccharides play a small yet crucial role in the functioning of different living beings.  Disaccharides are the most common, for example, sucrose is formed during photosynthesis, lactose is found in mammal milk which helps in the nourishment of the infant beings, Maltose is formed during the process of digestion by breaking down of starches, Trehalose is mostly found in insects and single-celled organisms. Hundreds of researches are going on around the world at the current times to discover and microanalyses not only Disaccharides and oligosaccharides but also other forms of carbohydrates.