PURIFICATION AND CHARACTERIZATION OF GLYCOPROTEIN FROM THE SKIN MUCUSOF THE RAINBOW-TROUT, SALMO-GAIRDNERI

Mucus glycoprotein (RGP) was purified and characterized from the skin mucus of rainbow trout, Salmo gairdneri. RGP was found to contain 30.1 % NeuAc, 26.0% GalNAc, 5.0% Gal, and 26.0% amino acids. The protein mo iety of RGP is very rich in Thr (32.4 mol%), Neither NeuGc nor KDN (2- keto-3-deoxy-D-glycero-D-galacto-nononic acid) was found in RGP. Alkal ine borohydride treatment of RGP yielded a major disaccharide alditol, NeuAc alpha 2c-->6GalNAc-ol and more than 4 minor oligosaccharide ald itols including NeuAc-->(GalNAc alpha 1-->)GalNAc-ol. It was evident t hat an average RGP molecule has approximately 500 NeuAc-containing oli gosaccharide chains, which are attached to the Thr and Ser residues of the protein moiety and spaced at an average of 3 amino acids apart.