RESUMO
Polysaccharide K4 expressed from E. coli K4 has a similar structure with chondroitin, which can be used as a precursor to produce chondroitin sulfates. Here, we investigated the structure, conformation and biological activity of K4 from an engineered strain with high productivity. The NMR analysis suggested that K4 from wild-type strain with a low yield was a partially fructosylated chondroitin. While K4 from engineered strain was a fully fructosylated chondroitin. Light scattering analysis gave the Mw values of 6.15â¯×â¯104, 8.23â¯×â¯104 and 1.92â¯×â¯104 for K4-1, K4-2 and defructosylated K4 (DK4), respectively. The exponents of functions