Purification, structural characterization and bioactivity evaluation of a novel proteoglycan produced by Corbicula fluminea

A novel proteoglycan, named CFPS-11, was isolated from Corbicula fluminea, which is a food source of freshwater bivalve mollusk. CFPS-11 had an average molecular weight of 807.7 kDa and consisted of D-glucose and Dglucosamine in a molar ratio of 12.2:1.0. The protein moiety (similar to 5%) of CFPS-11 was covalently bonded to the polysaccharide chain in 0-linkage type through both serine and thereonine residues. The polysaccharide chain of CFPS-11 was composed of (1 -> 4)-alpha-D-glucopyranosyl and (1 -> 3,6)-alpha-D glucopyranosyl residues, which branched at O-6. The branch chain consisted of (1 ->)-alpha-D glucopyranosyl and (1 ->)-alpha-D-N acetylglucosamine residues. CFPS-11 exhibited significant antioxidant activity in a dose-dependent manner and remarkable inhibition activities against alpha-amylase and alpha-glucosidase by in vitro assays. These findings indicated that the CFPS-11 from C. fluminea has the potential for development as a health food ingredient.