Toward a biotechnological heparin through combined chemical and enzymatic modification of the Escherichia coli K5 polysaccharide

A process to generate glycosaminoglycans with heparin- and heparan sulfate- like sequences from the Escherichia coli K5 capsular polysaccharide is desc ribed. This polymer has the same structure as N-acetylheparosan, the precur sor in heparin/ heparan sulfate biosynthesis. The process involves chemical N-deacetylation and N-sulfation, enzymatic conversion of up to 60% of the D-glucuronic acid to L-iduronic acid residues, and chemical O-sulfation. Be cause direct sulfation afforded unwanted 3-O-sulfated (instead of 2-O-sulfa ted) iduronic acid residues, a strategy involving graded solvolytic desulfa tion of chemically oversulfated C5-epimerized sulfaminoheparosans was asses sed using persulfated heparin and heparan sulfate as model compounds. The O -desulfation process was shown to increase the anti-factor Xa activity of o versulfated heparin.