Structure, rheology, and copper-complexation of a hyaluronan-like exopolysaccharide from Vibrio.

• An exopolysaccharide (EPS) was isolated from bacterial mats in French Polynesia. • The structure repeating unit is →4)-b-D-GlcpA-(1→4)-a-D-GalpNAc-(1→3)-b-D-GlcpNAc-(1→4)-b-D-GlcpA-(1→. • MO245 has equal ratio of GlcA to N-acetylated sugars and the same glyosidic linkages than HA. • The structural similarity to HA provides MO245 with similar physicochemical properties. MO245 exopolysaccharide (EPS) was produced in laboratory conditions from Vibrio genus microorganism isolated from bacterial mats found in Moorea Island. Its structure consists of a linear tetrasaccharide repeating unit →4)-β-D-Glc p A-(1→4)-α-D-Gal p NAc-(1→3)-β-D-Glc p NAc-(1→4)-β-D-Glc p A-(1→ containing covalently-linked 5% of glucose, galactose, and rhamnose, determined by methylation analyses and NMR spectroscopy. The molecular weight, radius of gyration (R g) and intrinsic viscosity, [ η ], determined by gel permeation chromatography with light scattering and viscosity detection, were 513 ± 4 kDa (PDI, 1.42 ± 0.01), 6.7 ± 0.3 dl/g and 56 ± 0.3 nm respectively. The chelation of the EPS with copper divalent ions leads to the instantaneous formation of gels. The structural similitude proposed, based in an equal ratio of GlcA to N-acetylated sugars and in the same type of glyosidic linkages present in the repeating unit (alternated 1→3 and 1→4 linkages), is translated into analogous physicochemical properties: MO245 EPS is a flexible polyelectrolyte, with scaling exponents similar to that described for HA. This similitude opens opportunities in future drug delivery, tissue engineering, and cosmetic applications. [ABSTRACT FROM AUTHOR]