The Amino-Acid and Carbohydrate Sequences of a Short Glycopeptide Isolated from Bovine kappa-Casein

Abstract

A short glycopeptide was isolated from bovine χ-casein by enzymic digestions, filtrations on Sephadex G-25 and was electrophoretically homogeneous. An O-glycosidic linkage was characterized between a residue of threonine and N-acetylgalactosamine. By chemical and enzymic proce- dures, the following formula was established: where NeuNAc =N-acetylneuraminic acid. The phosphoserine residue of χ-caseinoglycopeptide was characterized in the short glycopeptide which was localized in the C-terminal part of χ-casein. Thr-X-Pro might be suggested as “code sequence” for glycopeptides containing an O-glycosidic linkage.