Treatment of pronase-cleaved glycopeptides derived from milk fat globule membrane with alkaline borohydride released a reduced oligosaccharide fraction from which a tetrasaccharide and two trisaccharides were isolated. Periodate oxidation studies coupled with methylation analysis and g.l.c. mass spectrometry established their structure as: N-acetylneuraminyl- (23)-D-galactopyranosyl-(13) - [N-acetylneuraminyl-(26)] -N-acetyl-D-galactosaminitol, N-acetylneuraminyl-(23)-D-galactopyranosyl-(13)- N-acetyl-D-galactosaminitol and -D-galactopyranosyl-(l3) -[N-acetyl-neuraminyl- (26)] -N-acetyl-D-galactosaminitol respectively. Fractionation of the pronase-cleaved peptide mixture, gave a homogeneous sialoglycopeptide which was characterised by gel fitration and SDS-PAGE. Alkaline borohydride treatment of this sialoglycopeptide released the tetrasaccharide and disaccharides isolated in the first part of the work. The carbohydrate content of the sialoglycopeptide was examined by gas chromatography and lectin agglutination studies. Sugars exposed on the surface of the intact milk fat globule were studied by an agglutination technique developed for the purpose and the results were related to those of the purified sialoglycopeptide. The contribution of the sialoglycopeptide to the antigenicity of the milk fat globule membrane was briefly investigated.
|Date of Award||1978|