ANALYSIS OF SERINE THREONINE-LINKED OLIGOSACCHARIDES DERIVED BY ALKALINE-BOROHYDRIDE TREATMENT OF MUCIN GLYCOPROTEINS ELECTROBLOTTED ONTO MEMBRANES - COMPARISON OF THE SACCHARIDE PROFILES OF THE 390 KDA AND 350 KDA FORMS OF EPITECTIN/

Alkaline borohydride treatment is widely used for the release of carbo hydrate moieties from O-glycosylated glycoproteins and mucins. We have adapted this procedure to micro quantities of glycoproteins blotted o n membranes. After electrophoresis and transfer to nitrocellulose, nyl on or polyvinylidene difluoride membrane, alkaline borohydride treatme nt was done directly on glycoprotein containing areas of membrane whic h were cut out with the aid of guide strips stained with Coomassie Blu e or lectin-digoxigenin. In combination with standard saccharide fract ionation techniques, this procedure can be used to characterize the ol igosaccharides of mucins or mucin-type glycoproteins that are separate d by gel electrophoresis from crude sources. Using this approach we ha ve characterized the saccharides derived from the two species of epite ctin, a malignancy-associated mucin type glycoprotein, isolated from m etabolically labelled H.Ep2 cells.