Heparan Sulfate - HS Structure and Differences From Heparin

HS Structure and Differences From Heparin

Heparan sulfate is a member of the glycosaminoglycan family of carbohydrates and is very closely related in structure to heparin. Both consist of a variably sulfated repeating disaccharide unit. The main disaccharide units that occur in heparan sulfate and heparin are shown below.

The most common disaccharide unit within heparan sulfate is composed of a glucuronic acid (GlcA) linked to N-acetylglucosamine (GlcNAc) typically making up around 50% of the total disaccharide units. Compare this to heparin where IdoA(2S)-GlcNS(6S) makes up 85% of heparins from beef lung and about 75% of those from porcine intestinal mucosa. Problems arise when defining hybrid GAGs that contain both 'heparin-like' and 'HS-like' structures. It has been suggested that a GAG should qualify as heparin only if its content of N-sulfate groups largely exceeds that of N-acetyl groups and the concentration of O-sulfate groups exceeds those of N-sulfate.

Not shown below are the rare disaccharides containing a 3-O-sulfated glucosamine (GlcNS(3S,6S) or a free amine group (GlcNH3+). Under physiological conditions the ester and amide sulfate groups are deprotonated and attract positively charged counterions to form a salt. It is in this form that HS is thought to exist at the cell surface.

  • GlcA-GlcNAc
  • GlcA-GlcNS
  • IdoA-GlcNS
  • IdoA(2S)-GlcNS
  • IdoA-GlcNS(6S)
  • IdoA(2S)-GlcNS(6S)

Read more about this topic:  Heparan Sulfate

Famous quotes containing the words structure and/or differences:

    “I really do inhabit a system in which words are capable of shaking the entire structure of government, where words can prove mightier than ten military divisions.”
    —Václav Havel (b. 1936)

    “Toddlerhood resembles adolescence because of the rapidity of physical growth and because of the impulse to break loose of parental boundaries. At both ages, the struggle for independence exists hand in hand with the often hidden wish to be contained and protected while striving to move forward in the world. How parents and toddlers negotiate their differences sets the stage for their ability to remain partners during childhood and through the rebellions of the teenage years.”
    —Alicia F. Lieberman (20th century)