Unsaturated K5 Disaccharide

K5 polysaccharide from E. coli K5, composed of [→4)-β-D-glucuronic acid (GlcA)-(1→4)-N-acetyl-α-D-glucosamine (GlcNAc)-(1→]n, offers a promising precursor for generation of a bioengineered heparin using chemoenzymatic modification. The unsaturated K5 disaccharide with Δ4,5GlcA at the non-reducing end is obtained by the enzymolysis of K5 polysaccharide with K5 lyase A ). The identity of degradation products was confirmed by reversed-phase ion-pairing high performance liquid chromatography (RPIP-HPLC) detected at 232 nm, and electrospray ionization (ESI)-MS. The disaccharide can be used as substrate for heparin synthesis, and standard in chemical and biological experiments as well.