What are glycans?

What are glycans?

Glycans are substances that consist of monosaccharides connected in chains. There are many types of monosaccharides, including glucose, mannose, sialic acid, fucose, and N-acetylglucosamine. These monosaccharides link together by glycosidic bondings to form glycans. A wide variety of glycan structures can be formed, depending on the type and number of monosaccharides, and the way of glycosidic bonding. The glycan of a glycoprotein is classified according to the amino acid to which it is bonded. A glycan attached to the hydroxy group of serine or threonine is called an O-linked glycan, and a glycan attached to the amino group of asparagine is called an N-linked glycan.

Glycans are closely related to life activities

In living organisms, glycans are found linked to proteins and lipids on cell surfaces and inside cells. Along with nucleic acids and proteins, these glycans comprise “the third life chain” because of their involvement in various vital phenomena.

A familiar example is ABO blood groups, which are classified according to the structure of the glycans attached to the surface of red blood cells. A red blood cell is classified as type O if its sole glycan attachment consists of a core structure formed by the three monosaccharides: fucose, galactose, and N-acetylglucosamine. A cell that has the core structure plus N-acetylgalactosamine is type A, and one that has the core structure plus galactose is type B. (Red blood cells with both type A and type B glycans are classified as type AB.) People with type A glycans (people with type A blood) also have antibodies in their blood that attack type B glycans as foreign substances (anti-B antibodies). Therefore, if a person with type A blood receives a transfusion of type B or AB, anti-B antibodies react and destroy the blood. This is why transfusions are basically matched to the blood type of the recipient.

Glycans and diseases

Glycans linked to proteins and lipids are known to affect the function and stability of the substances to which they are linked. Glycans existing on the cell surface also play roles in various vital phenomena such as cell adhesion and differentiation. Many diseases and disorders are caused by glycan abnormalities.
For example, influenza viruses are known to cause infection by recognizing specific glycan structures attached to the surface of human cells. Allergic symptoms such as hay fever may also be caused by glycans attached to allergen molecules.

KH Neochem’s glycan technologies

As the third life chain, glycans have been actively investigated in life science fields to elucidate vital phenomena and develop new drugs, but artificial synthesis of glycans is difficult because of the great diversity of glycan structures. Providing a large and stable supply of glycans remains a challenge to the further promotion of academic research and industrial use of glycans. KH Neochem has developed its own glycan manufacturing technologies with the aim of providing a stable and large supply of various types of glycans to promote academic research and accelerate industrial use of glycans.