Structural characterisation of chondroitin sulphate from Italian cheese Parmigiano-Reggiano

摘要

Chondroitin sulphate (CS) was purified for the first time from the Italian cheese Parmigiano-Reggiano and analysed to evaluate its structure and properties. Two main polysaccharides were identified as CS, ~72%, and fast moving-heparin/heparan sulphate, ~28%. Quantitative analyses yielded ~1.5-3.0 ug of total GAGs per gram of Parmigiano-Reggiano (0.15-0.30%). By means of specific chondroitinases and HPLC separation of generated unsaturated disaccharides, CS was found to be composed of ~9% of nonsutphated disaccharide, ~26% of disaccharide monosulphated in 6 of the GalNAc, ~65% of disaccharide monosulph-ated in 4 of the GalNAc, with a charge density of ~0.91 and a 4/6-sulphated ratio of 2.45. The ratio of 4/6 sulphated residues was confirmed by ~(13)C NMR experiments. Susceptibility to cleavage catalysed by chon-droitinase B confirmed that the purified Parmigiano-Reggiano CS contains mainly GlcA (~94%) as uronic acid. PAGE analysis showed a CS having a molecular mass with an average value of 15400.