Heparan Sulphates

Heparan Sulphate - Guidance notes

Heparan sulphate (HS) is widely recognised as the major glycosaminoglycan on cell surfaces; it is an essential co-receptor for many growth factors, morphogenic proteins and signalling structural elements in the extracellular matrix such as fibronectin and various types of collagen. It has a distinctive molecular organisation in which sulphated domains are spaced along the polymer chain separated by regions that are largely devoid of sulphate groups. Despite sharing a common design the HS fine structure is often typical of the cell of origin due to variability of sulphation patterns in the sulphated regions. This variability probably underpins specific protein binding activities at cell surfaces.

Kjellen, L. and Lindahl, U. (2018) Specificity of glycosaminoglycan-protein interactions. Current Opinion in Structural Biology 50:101–108

Gallagher J. (2015) Fell-Muir Lecture: Heparan Sulphate and the art of cell regulation: a polymer chain conducts the protein orchestra. Int J Exp Pathol. 96:203-231.

Xu D. and  Esko JD: (2014) Demystifying heparan sulfate-protein interactions. Annu Rev Biochem . 83:129-157.

To assist investigations of this most intriguing of glycosaminoglycans we offer several preparations of Heparan Sulphates that vary in molecular size and sulphation including a unique set of selectively-desulphated Heparan Sulphates. Please also see our heparin oligosaccharides that mimic some of the sulphation variability seen in HS.

Heparan Sulphate Polymer Fractions

1. Heparan Sulphate fraction I: Mol wt approx. 40kDa

Relatively low in Sulphation (when compared to parent GAG-HS01)/High Molecular Weight HS.

40 N-sulphate groups per 100 disaccharides 35 O-sulphate groups per 100 disaccharides *Polymer sulphation (N- and O-sulphate groups) is 75 per 100 disaccharides. The domain structure of this preparation is broadly similar to the most common form of heparan sulphate present on cell surfaces

2. Heparan Sulphate fraction III: Mol wt approx. 9kDa

High Sulphate/Low Molecular Weight HS.

65 N-sulphate groups per 100 disaccharides 110 O-sulphate groups per 100 disaccharides *Polymer sulphation (N- and O-sulphate groups) is 175 per 100 disaccharide

3. Heparan Sulphate

Heparan Sulphate isolated from porcine mucosa. This material contains both high and low sulphated species of HS and gives a bimodal molecular weight profile with fractions of approx. 40kDa and 9kDa; the smaller of the two fractions is the more sulphated component. This preparation has been separated by preparative SAX-hplc to give the three HS fractions listed above.

Heparan Sulphate Oligoaccharides

Excised by Specific Enzymes

Naturally-Occuring Structures

Analysis of HS domain Organisation

Heparan Sulphate (HS) is a near-universal co-receptor for many growth factors and morphogenic proteins; it has a complex domain organisation of alternating high and low sulphated regions (Fig 1) in which the various patterns of modification by sulphation by and epimerisation create considerable structural diversity designed for selective binding to its many client proteins.

We offer two classes of Heparan Sulphate Oligosaccharides (HS-oligos) prepared by:

Heparinase III digestion.
Hep III degrades the low sulphated regions of HS and is used to prepare oligos rich in the Heparinase III resistant high-sulphation domains (S-domains)

Heparinase I digestion.
Hep I acts in the S-domains of HS and is used to prepare oligos made from the enzyme-resistant regions of low/intermediate levels of sulphation.

The HS-oligos in the enzyme digests were separated by high resolution gel filtration and the molecular size profiles of the individual peaks assesed on Superdex S-75 hplc. Although substantially homogeneous on S-75 the HS-oligos in each size class will contains sequences that vary in composition and there may be some limited overlap with oligos in adjacent size groups.

Heparan Sulphate Polymers modified by specific chemical desulphation

These heparan sulphates (HS) were prepared by targeted desulphation of a highly-purified preparation of porcine heparan sulphate derived from intestinal mucosa. This material also has a domain structure like that of cell surface HS. Please note that this HS is a different preparation from the GAG-H01 that was used to prepare the HS fractions described above.

Standard chemical methods were used to selectively remove sulphate groups from C2 of iduronic acid (de2S HS), C6 of glucosamine (de6S HS) or the N-sulphate from N-sulphated glucosamine (deNS HS); the deNS HS contains free amino groups due to the loss of N-sulphates. In deNS/Ac HS the free amino groups have been acetylated. 

Gel filtration profiles of the modified HS on Superdex S-75 hplc revealed only very minor reductions in molecular size compared to the parental material probably due to the loss of sulphate groups.

With the exception of 6-O desulphated HS the procedures lead to the loss of over 95% of the targeted sulphate groups.

6-O desulphated HS; in this preparation the reduction in 6-O-sulphate groups was 70%. 6-O-sulphates were completely removed from the trisulphated disaccharide (UA,2S – GlcNS,6S) but the targeted desulphation of UA – GlcNAc,6S and UA – GlcNS,6S was incomplete (50% and 70% loss of 6-O-sulphates respectively). 

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Disaccharide analysis of selectively desulphated Heparan Sulphates: comparison of parental material with the desulphated preparations.