Building Block Analysis of ATIII Affinity Fractions of Heparins: Application to the ATIII Binding Capacity of Non-conventional 3-O-Sulfated Sequences

Thrombin and Factor Xa Hydrolysis of Chromogenic Substrates in the Presence of Sulfated Derivatives of Galactomannan and Galactoglucomannan Natural Gels

Polysaccharides are important structural components of all plant species. Gel-like polysaccharides have found wide application in various fields, including medicine, construction, and the food industry. In the present work, galactomannan and galactoglucomannan gel-like polysaccharides were modified with sulfate groups and their anticoagulant activity was studied. Sulfation with chlorosulfonic acid in pyridine and with sulfamic acid in pyridine and a sulfamic acid-urea deep eutectic solvent were used as synthesis routes. The resulting gel-like polysaccharide sulfates were studied by elemental analysis, Fourier-transform infrared spectroscopy, and gel permeation chromatography. It was established that the anticoagulant effect of sulfated galactoglucomannan (SGGM) and galactomannan (SGM-1 and SGM-2) is related to an independent antithrombin-independent decrease in the amidolytic activity of thrombin and factor Xa. It is shown that the inhibitory activity of SGGM and SGM-2 against the collagen-induced platelet aggregation can be an additional factor in selecting compounds that are most promising for modifying polymer surfaces to ensure resistance to blood clotting.

Heparinase Digestion of 3-O-Sulfated Sequences: Selective Heparinase II Digestion for Separation and Identification of Binding Sequences Present in ATIII Affinity Fractions of Bovine Intestinal Heparins

Binding to antithrombin-III (ATIII) determines the anticoagulant activity of heparin. The complexes formed between heparin and ATIII result from a specific pentasaccharide sequence containing a 3-O-sulfated glucosamine in medium position. Building block analysis of heparins, following heparinase digestion, is a critical method in quality control that provides a simple structural characterization of a complex product. Hence, in these applications, study of the digestion of 3-O-sulfated moieties merits special attention. With heparinase II, specific inhibition of cleavage of the non-reducing bond of 3-O-sulfated units is observed. This specificity was erroneously generalized to other heparinases when it was observed that in exhaustive digests of heparins with the heparinase mixture, resistant 3-O-sulfated tetrasaccharides were also obtained from the specific ATIII-binding pentasaccharides. In fact, the detection of unsaturated 3-O-sulfated disaccharides in digests of heparin by heparinases I+II+III, resulting from the cleavage of the 3-O sulfated unit by heparinase I in non-conventional sequences, shows that this inhibition has exceptions. Thus, in experiments where heparinase II is selectively applied, these sequences can only be digested into tetra- or hexasaccharides where the 3-O-sulfated glucosamine is shifted on the reducing end. Heparinase I+II+III and heparinase II digests with additional tagging by reductive amination with sulfanilic acid were used to study the structural neighborhood of 3-O-sulfated disaccharides in bovine mucosal heparin fractions with increasing affinity for ATIII. The 3-O-sulfated disaccharides detected in heparinase I+II+III digests turn into numerous specific 3-O-sulfated tetrasaccharides in heparinase II digests. Additionally, ATIII-binding pentasaccharides with an extra 3-O-sulfate at the reducing glucosamine are detected in fractions of highest affinity as heparinase II-resistant hexasaccharides with two consecutive 3-O-sulfated units.