Heparinase III – 0.5 IU

Technical notes

Heparinase III (Heparitinase) acts on Heparan Sulphate in regions of low sulfation and it has little activity against heparin. The preferred substrates for heparinase III are N-Acetylated or N-sulfated glucosamines linked to glucuronic acid. (i.e. GlcNAc/ GlcNSO₃ 1 – 4 GlcA). In consequence it acts primarily in the non-sulfated domains (NAc domains) and transition zones of HS whereas the highly sulfated S-domains are resistant to Heparinase III. The enzyme tolerates C-6 sulfation of amino sugars. Heparinase III has weak activity with disaccharides containing Iduronic Acid (IdoA) and its action is blocked if the iduronate residue is sulfated at C-2 (IdoA, 2SO₃).

The Heparinase III resistant S-domains in HS have a heparin-like structure being mainly composed of GlcNSO₃ 1 – 4 IdoA,2SO₃ repeat units with variable O-sulfation at C-6 of the GlcNSO₃ residue. They vary in length form 3 to 9 disaccharide units. The patterns and densities of 6-O-sulfate groups along S-domains are an important determinant of their protein binding specificities.

The selectivity of Heparinase III can be exploited for the preparation of S-domains from HS. High resolution gel filtration will separate the different size classes of S-domain and these can be further subfractionated by SAX-HPLC according to sulfate content and patterning.