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| Semin Thromb Hemost 2007; 33: 466-477
DOI: 10.1055/s-2007-982077 |
Copyright © 2007 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA. |
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Structural Modification Induced in Heparin by a Fenton-Type Depolymerization Process |
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| Elena Vismara1, Monica Pierini1, Sara Guglieri2, Lino Liverani3, Giuseppe Mascellani3, Giangiacomo Torri2 |
1 G. Natta Chemistry Department, Polytechnic of Milan, Milan, Italy
2 Institute for Chemical and Biochemical Research “G. Ronzoni,” Milan, Italy
3 Opocrin SpA, Corlo di Formigine, Modena, Italy |
ABSTRACT
A low molecular weight heparin (LMWH) obtained by a depolymerization process induced by a Fenton-type reagent was characterized in depth by nuclear magnetic resonance (NMR) spectroscopy. The depolymerization involves the cleavage of glycosidic bonds, leading to natural terminal reducing end residues, mainly represented by N-sulfated glucosamine (ANS). Natural uronic acids, especially the 2-O-sulfate iduronic acid (I2S), are also present as reducing residues. A peculiar reaction results, such as the disappearance of the nonsulfated iduronic acid residues when followed by 6-O-nonsulfated glucosamine, and the decrease of the glucuronic acid when followed by the N-acetylglucosamine, were observed. Iduronic acid residues, followed by 6-O-sulfate glucosamine (ANx,6S), and the glucuronic acid residues, followed by ANS residues, were not modified. A few minor internal chain modifications occur, possibly arising from oxidative breaking of the bond between C2-C3 of glucosamine and uronic acids, suggested by evidence of formation of new -COR groups. Finally, no change was observed in the content of the N-sulfated, 6-O-sulfated glucosamine bearing an extra sulfate on 3-O, which is considered the marker of the active site for antithrombin. With respect to the original heparin, this LMWH is characterized by a lower number of nonsulfated uronic acid residues, and as a consequence, by a lower degree of structural heterogeneity than LMWHs prepared with other procedures.
KEYWORDS
Low molecular weight heparin (LMWH) - radical depolymerization - nuclear magnetic resonance; Fenton-type reagent
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