Other Methods of Desulfation

In 1938, Egami reported that n-glucose monosulfate (prepared from D-glucose by direct sulfation) is hydrolyzed slowly in aqueous solutions of hydrazine or related organic reagents. Further studies educed the fact that a purified preparation of D-glucose 6-sulfate is desulfated only slowly by M hydrazine at pH 6, whereas an impurity, present in crude preparations of the 6-sulfate, is hydrolyzed at a much higher rate.  

The action of aqueous hydrazine on sugar sulfates is different from that of anhydrous hydrazine on sulfated polysaccharides of the chondroitin type. Anhydrous hydrazine is a reagent for cleaving the amide linkage in, for instance, proteins. It has been applied to chondroitin A sulfate to effect Af-deacetylation, and then gave a partly desulfated, as well as N-deacetylated, polymer. In contrast, the aqueous hydrazine reagent has no effect on chondroitin sulfates A and C.  

Finally, mention should be made of another kind of sulfatase, extracted from a red alga. This sulfatase is not a hydrolase, but converts residues of L-galactose 6-sulfate within a particular polysaccharide, porphyran, into 3,6-anhydro-L-galactose residues, thus simulating the action of alkali. It is not yet known whether this enzyme will function on suitably sulfated oligosaccharides, or whether it is specific for the polysaccharide sulfate, porphyran. 

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