Fluorometric determination of mucin-type glycoproteins by the galactose oxidase-peroxidase method

We developed a convenient and specific method for the determination of muci n-type glycoproteins using galactose oxidase and horseradish peroxidase on the basis of the contents of galactosyl and N-acetylgalactosaminyl residues in glycoproteins. Galactose and galactosamine residues released from glyco proteins after hydrolysis were oxidized with galactose oxidase and subseque ntly the resultant hydrogen peroxide was determined by a combination of hor seradish peroxidase and 3-(p-hydroxyphenyl) propionic acid as a fluorogenic substrate, The contents of galactose/galactosamine residues in N- and O-gl ycans, as determined by the galactose oxidase-peroxidase method, were in go od agreement with those described in the previous reports. We applied the p resent method to determine mucin-type glycoproteins secreted from rat gastr ic mucosa by stimulation with misoprostol, a prostaglandin E-1 analogue in vivo. Thus, the galactose oxidase-peroxidase: method is useful for the dete rmination of mucin-type glycoproteins in biological materials. (C) 2000 Aca demic Press.