Highly sulfated derivatives of K5 polysaccharide and their preparation

Abstract

The purification of the E. coli K5 polysaccharide by treatment with isopropyl alcohol and elimination of lipophilic substances is described. The purified product can be used to prepare, after N-deacetylation, new N,O-sulfated polysaccharides with high degree of sulfation.

1 .- 13 . Canceled.  
     
     
         14 . Pure K5 polysaccharide substantially free from lipophilic substances, or a salt thereof.  
     
     
         15 . The pure K5 of  claim 14 , showing no signals in the region below 1.5 ppm of the  1 H-NMR spectrum.  
     
     
         16 . The K5 polysaccharide of  claim 15 , wherein nucleic acids are not detectable in the UV spectrum at 260 nm and the protein content is below 0.5%.  
     
     
         17 . Substantially free from lipophilic substances K5 polysaccharide obtainable according to a process wherein (a1) a K5 from fermentation, dissolved in 4 M sodium chloride solution at 4° C., is treated with 1 volume of isopropanol; (a2) the salt solution is brought to a 3 M concentration by addition of the calculated amount of sodium chloride; (a3) the solution is kept overnight at 4° C.; and (a4) the product is isolated by centrifugation and the salts are eliminated by ultrafiltration.  
     
     
         18 . A N,O-oversulfated K5 polysaccharide having a sulfation degree higher than 3.2 obtainable according to the process consisting of 
 (a) treating a K5 from fermentation with isopropanol in a highly salt aqueous solution;    (b) submitting the thus purified K5 to a N-deacetylation followed by a subsequent N-sulfation by treatment with a N-sulfating agent;    (c) treating an ammonium salt of the N-sulfate K5 thus obtained with an O-sulfating agent under O-oversulfation conditions; and    (d) if necessary submitting the product thus obtained to a N-sulfation and isolating the N,O-oversulfated K5 in form of its sodium salt which, if necessary, is converted into another salt.    
     
     
         19 .- 33 . Canceled.