Heparin - Heparin Structure

Heparin Structure

Native heparin is a polymer with a molecular weight ranging from 3 kDa to 30 kDa, although the average molecular weight of most commercial heparin preparations is in the range of 12 kDa to 15 kDa. Heparin is a member of the glycosaminoglycan family of carbohydrates (which includes the closely related molecule heparan sulfate) and consists of a variably sulfated repeating disaccharide unit. The main disaccharide units that occur in heparin are shown below. The most common disaccharide unit is composed of a 2-O-sulfated iduronic acid and 6-O-sulfated, N-sulfated glucosamine, IdoA(2S)-GlcNS(6S). For example, this makes up 85% of heparins from beef lung and about 75% of those from porcine intestinal mucosa. 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 heparin salt. It is in this form that heparin is usually administered as an anticoagulant.

One unit of heparin (the "Howell Unit") is an amount approximately equivalent to 0.002 mg of pure heparin, which is the quantity required to keep 1 mL of cat's blood fluid for 24 hours at 0 °C.

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