Conformational inversion of some sulfated mucopolysaccharides

Effect of sulfated derivatives of chitosan on some blood coagulant factors

The effect of some sulfated derivatives of chitosan on several blood-coagulant factors was examined in comparison with those of heparin (174 units/mg). The anticoagulant activity (units/mg) with respect to activated partial thromboplastin time was 331-379 for O-sulfated N-acetylchitosan (2), 190-287 for N, O-sulfated chitosan (1), and 21-31 for sulfated O-carboxymethylchitosan (3). The activity (units/mg) with respect to thrombin time was 70-87 for 2, 44-70 for 1, and 14-22 for 3. The activity (units/mg) with respect to antithrombin activity was 4.9-9.0 for 2, 4.7-8.7 for 1, and 3.3-6.0 for 3. No anti-(factor Xa) activity was observed with 1-3. A 6-sulfate group in the hexosaminyl moiety was a main active site; although a 3-sulfate group was not essential, it promoted the activity of the 6-sulfate group. N-Sulfate was not a prerequisite for activity. The biological activities were also related to molecular weight in the sequence 2 (26,000) greater than heparin (21,000) greater than 1 (12,000) greater than 3 (540,000). For the Methylene Blue complexes, 1, but neither 2 nor 3, exhibited a negative, induced Cotton effect similar to that of heparin.

The binding of chondroitin 6-sulfate to plasma low density lipoprotein

The interaction in vitro of several sulfated glycosaminoglycans with low density lipoproteins (LDL) has been studied. Chondroitin 6-sulfate and heparin were the only ones to produce turbidity when added to LDL in presence of Ca2+. However, when these two glycosaminoglycans were applied to LDL-affinity columns in presence of Ca2+, only chondroitin 6-sulfate was retained. Partially desulfated chondroitin 6-sulfate was not retained on LDL-affinity column, indicating the relevance of sulfate groups in the binding of LDL. Since chondroitin 4-sulfate and heparin, with a sulfate content respectively equal to and greater than that of chondroitin 6-sulfate, are not retained on LDL-affinity columns, the factors relevant to the binding of LDL are probably the conformation of the glycan in solution and the orientation of its sulfate groups.

Glycosaminoglycans: structure and interaction

In the last few years, there has been considerable progress in the studies on glycosaminoglycans, a group of acidic polysaccharides present in the intercellular matrix of connective tissue. X-ray diffraction studies have indicated that these polymers can exist in the condensed phase in some helical form. Chiroptical and hydrodynamic measurements have provided significant information regarding the molecular conformation in solution and other physicochemical properties of the polymers. Studies related to the interaction properties of glycosaminoglycans with polypeptides, metal ions, and other molecules are numerous. This review covers mainly the results and their interpretations of both published and as yet unpublished material of the 1970s, but certain previous data are also included. A present-day concept regarding the structure and interaction properties of these molecules on the basis of various physicochemical measurements is presented. The biosynthesis and metabolism of glycosaminoglycans, and the structure of proteoglycans and glycoproteins, are not discussed.