Heparin 3-eliminative degradation

This fragmentation of the heparin heteropolysaccharide chain proved to be a jS-elimination reaction in which diazomethane acts as the proton acceptor. It is interesting that aryldiazoalkanes (for example, phenyl or substituted-phenyl diazomethanes) cannot be used for a similar j8-eliminative degradation of quaternary ammonium salts of sulfated heteropolysaccharides. 

In this diazoalkane-catalyzed, -eliminative degradation of quaternary ammonium salts of heparin, it was not proved whether it is the l-iduronate or the n-glucuronate residues that react, to form the terminally linked, unsaturated hexopyranuronate residue in the oligosaccharide fragments. 

It was furthermore reported that the esterification of pectic acid by use of diazomethane is concomitant with the /3-eliminative degradation of the D-galacturonan chain. Oligosaccharides were obtained possessing the terminally linked, unsaturated deoxyhexopyranuronate residue, similar to the analogous degradation of heparin quaternary ammonium salts already described. 

Hence, the stereochemistry of the 8-eliminative degradation of alginic acid seems to be similar to that of the heteropolysaccharide chain of heparin. As already described, in tbe latter 8-eliminative degradation, both the D-glucopyranuronate and the L-idopyranuronate, possessing the same stereochemical disposition of the groups on C-5 and C-4 of the ring, are involved. 

Alkali-catalyzed cleavage of glycosidic bonds of glycosaminoglycur-onates occurs by way of -elimination.223 By proper choice of the experimental conditions, it seems possible to achieve a controlled degradation of heparin by -elimination, producing fragments apparently preserving... 

Heparinase, an enzyme that degrades heparin into small polysaccharides, has also been immobilized into an extracorporeal device (artificial kidney bioreactor) to eliminate the anticoagulant properties of heparin (used to prevent clotting in the device) before the blood returns to the patient. ... 

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