Glycan

Glycan is a complex biomolecule composed of a chain of carbohydrate residues bonded covalently. Glycans play a crucial role in various biological functions, including cell-cell interaction, immune response, and pathogen recognition. They are found in all living organisms and are essential components of cell membranes, proteins, and lipids.

Structure

Glycans are composed of monosaccharide units linked together by glycosidic bonds. The structure of a glycan can be linear or branched, and it can vary in terms of the number and type of monosaccharide units, the length of the chain, and the type of glycosidic bond. The most common monosaccharides found in glycans are glucose, galactose, mannose, fucose, and sialic acid.

Function

Glycans play a crucial role in various biological functions. They are involved in cell-cell interaction, immune response, and pathogen recognition. Glycans attached to proteins (glycoproteins) or lipids (glycolipids) can act as receptors for pathogens, allowing the immune system to recognize and eliminate them. Glycans also play a role in cell adhesion, cell signaling, and the modulation of protein function.

Types of Glycans

There are several types of glycans, including N-linked glycans, O-linked glycans, and glycosaminoglycans. N-linked glycans are attached to the amide nitrogen of asparagine residues in proteins, while O-linked glycans are attached to the hydroxyl oxygen of serine or threonine residues. Glycosaminoglycans are long, unbranched polysaccharides composed of repeating disaccharide units.

Glycan Biosynthesis

Glycan biosynthesis involves the action of various enzymes, including glycosyltransferases, which catalyze the formation of glycosidic bonds, and glycosidases, which catalyze the hydrolysis of these bonds. The biosynthesis of glycans is a complex process that is tightly regulated by the cell.

Glycan Analysis

The analysis of glycans is a challenging task due to their structural complexity and diversity. Various techniques, including mass spectrometry, nuclear magnetic resonance spectroscopy, and high-performance liquid chromatography, are used for glycan analysis.

See Also

• Glycosylation
• Glycoprotein
• Glycolipid
• Glycosyltransferase
• Glycosidase

Glycan Resources
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