Effect of carbohydrate moieties on the stability of nuclear glycoproteins from hamster liver

The effect of carbohydrate moieties on the stability of hamster liver nuclear glycoproteins in the course of endogenous proteolysis employing highly specific digoxigenin-labelled lectins, was studied. Whole hamster liver nuclei were autolysed in optimum conditions for the action of nuclear proteinases able to degrade histones as well as non-histone proteins. Incubated samples were electrophoresed on sodium dodecyl sulphate-polyacrylamide gel. Coomassie blue stained gels demonstrated degradation of some proteins in particular after 18 and 24 h incubation. Proteins with molecular weights of about 46, 54 and 76 kD appeared to be resistant to proteolysis. The same location and intensity of bands of glycoproteins on immunoblots from incubated and nonincubated samples of nuclei indicated that oligosaccharide chains protect proteins from degradation.