Structural modification induced in heparin by a Fenton-type depolymerization process.
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 (A (NS)). Natural uronic acids, especially the 2- O-sulfate iduronic acid (I (2S)), 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 (A (Nx,6S)), and the glucuronic acid residues, followed by A (NS) 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.
Vismara
Elena
E
G. Natta Chemistry Department, Polytechnic of Milan, V. Mancinelli 7, 20131 Milan, Italy. elena.vismara@polimi.it
Pierini
Monica
M
Guglieri
Sara
S
Liverani
Lino
L
Mascellani
Giuseppe
G
Torri
Giangiacomo
G
D005609:Free Radicals / Q000737:chemistry*; D006495:Heparin, Low-Molecular-Weight / Q000737:chemistry*; D007067:Iduronic Acid / Q000737:chemistry*; D015394:Molecular Structure; D010084:Oxidation-Reduction
D005609:Free Radicals; D006495:Heparin, Low-Molecular-Weight; D007067:Iduronic Acid