Constituent Monosaccharides of Oligosaccharides

Introduction

The oligosaccharide comes from the Greek word oligosaccharides, which means “some saccharides.” The unit structure of carbohydrates is referred to as a saccharide. An oligosaccharide is a carbohydrate made up of a small number of saccharides, usually three to ten (mono)saccharide units. An oligosaccharide’s number of monomer units is not precisely specified. According to some sources, carbohydrates with two to ten monosaccharide units are considered oligosaccharides, including disaccharides (saccharides made up of two monosaccharide units). Other sources define oligosaccharides as carbohydrates consisting of three to six monosaccharide components.

Characteristics of oligosaccharides

Polysaccharides, like other carbohydrates, consist of hydrogen, carbon, and oxygen. The ratio of hydrogen to oxygen atoms in polysaccharides is frequently 2:1, which is why they’re called carbohydrates. Oligosaccharides, like other carbohydrates, are organic substances since they include carbon and C-C and C-H covalent bonds. An oligosaccharide, on the other hand, consists of an elongated joint of monomeric saccharide units (which has only one saccharide unit) or a disaccharide (which has only one saccharide unit) (comprising two saccharides). Despite this, it is much smaller than a polysaccharide (which includes more than ten saccharide units).

Dehydration synthesis refers to the chemical process of connecting monosaccharide units that result in the release of water as a byproduct. The oligosaccharide consists of monosaccharide molecules joined together by glycosidic linkages. Covalent connections between the hydroxyl groups of two monosaccharides are called glycosidic bonds. Many oligosaccharides found in nature are related to other biomolecules, such as proteins, peptides, or lipids.

Classifications of Oligosaccharides

Let’s discuss some of them for more information on constituent monosaccharides of oligosaccharides (sucrose, lactose and maltose).

Three monosaccharides make up trisaccharides, which are oligosaccharides. nigerotriose (glucose-fructose-glucose), maltotriose (glucose-glucose-fructose), melezitose (glucose-fructose-glucose), maltotriose (glucose-glucose-fructose), raffinose (galactose-glucose-fructose) (glucose-fructose-fructose).

Tetrasaccharides are four monosaccharide-based oligosaccharides. nigerotetraose (4 glucose units connected by (13) glycosidic linkage), maltotetraose (4 glucose units joined by (14) glycosidic linkage), lychnose (galactose-glucose-fructose-galactose), nystose (glucose-fructose-fructose), sesamose (galactose-galactose (galactose-galactose-glucose-fructose).

On the other hand, disaccharide contains a maltose structure made up of two α-D-glucose units connected by glycosidic linkage.

Common oligosaccharides

Raffinose and stachyose are two prevalent oligosaccharides.

Galactose, glucose, and fructose are the three monomers that make up this trisaccharide. C18H32O16 is its chemical formula. As a result, it’s a trisaccharide. It produces D-galactose and sucrose when hydrolyzed by the enzyme galactosidase. Raffinose can be found in legumes, whole grains, cabbage, Brussel sprouts, broccoli, cottonseed, beetroot molasses, asparagus, and other foods.

Raffinose is merely one of the RFOs’ members (raffinose family of oligosaccharides). Other members include tetrasaccharide stachyose and pentasaccharide verbascose. They’re made from sucrose and include galactose moieties from galactinol. RFOs are prevalent in plants and act as a desiccant in seeds, transport sugar in phloem sap, and storage sugars.

Plants have a lot of storage oligosaccharides, like fructooligosaccharides. Fructooligosaccharides (also known as oligofructans) are found in various plants, particularly the blue Agave, Jerusalem artichoke, and yacón. They’re employed as sweeteners and additives in the food industry.

Biological Importance

Before knowing the constituent monosaccharides of oligosaccharides (sucrose, lactose and maltose), it’s important to note that dietary oligosaccharides are an essential energy source. Fructooligosaccharides are an excellent source of dietary fibre in particular. Plants that generate them (most notably blue Agave, Jerusalem artichoke, and yacón) extract them. Bananas, leeks, onions, garlic, and asparagus are among the edible fruits and vegetables that contain them. They act as storage oligosaccharides in these plants. They are mainly used as prebiotics in humans. Dietary oligosaccharides originating from dairy, notably galacto-oligosaccharides and human milk oligosaccharides, play a similar purpose.

Glycan components of glycoproteins are made up of several oligosaccharides. Proteins covalently connected to a carbohydrate, particularly an oligosaccharide, are known as glycoproteins. They’re made up of glycosylation. The -OH group of serine or threonine (i.e., O-glycosylated) or the amide NH2 of asparagine attaches the carbohydrate component to the protein (i.e., N-glycosylated). Antigenicity, solubility, cell adhesion, cell recognition, and immunological function are tasks performed by glycoproteins containing oligosaccharides.

Conclusion

Monosaccharide and oligosaccharide derivatives play a vital part in biological processes. Furthermore, monosaccharides, oligosaccharides, and their derivatives are essential compounds with various biological activities, including anticancer, antiviral, insecticidal, antibacterial, and antioxidant capabilities.