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Carbohydrate moiety of Plasmodium falciparum glycoproteins: the nature of the carbohydrate-peptide linkage in the MSP-2 glycoprotein

Khan, A. H.
Qazi, A. M.
Torred-Duarte, A. P.
Senaldi, G.
Qazi, M. H.
Walker-Nasir, Evelyne
Nasir ud, Din
Published in Biochemistry & Molecular Biology International. 1997, vol. 43, no. 3, p. 655-668
Abstract Metabolic labelling of Plasmodium falciparum parasites with [3H]GlcN, [3H]Man, [3H]Gal and [3H]ethanolamine, and subsequent purification by SDS-PAGE of the labelled material provided effective labelling of the MSP-1, 195 kDa, and MSP-2, 42-53 kDa, glycoproteins. Reductive beta-elimination of the MSP-2 released from the gel consisted of glycopeptides containing labelled sugars. Processing of the eliminated components and identification of the sugar residues demonstrated the presence of N-acetylglucosaminitol and N-acetylgalactosaminitol amongst other labelled sugars. Reductive beta-elimination with sodium hydroxide-sodium borotritide-borohydride showed the presence of glucosaminitol and alanine in the hydrolysis products. The MSP-2 was retained on solid phase wheat-germ agglutinin and was released from the lectin by treatment with GlcNAc. Upon treatment with O-glycanase the MSP-2 glycoprotein released labelled amino sugar, and derived oligosaccharides on treatment with exoglycosidases released labelled components corresponding to the metabolically incorporated sugars. Labelled Gal was incorporated into the MSP-2 glycoprotein using [3H]UDP-Gal and galactosyltransferase. The galactosylated glycoprotein released labelled Gal upon treatment with beta-galactosidase. The results of the present study suggest that the carbohydrate chains of the MSP-2 glycoprotein are attached to the protein backbone via GlcNAc- and GalNAc-serine/threonine in O-glycosyl linkage and the glycoprotein has terminal GlcNAc and Gal residues. The carbohydrate moieties of MSP-2, glycoprotein consist mainly of short chains linked to the protein core.
Keywords AnimalsAntigens, BacterialBacterial Outer Membrane ProteinsBacterial Proteins/ chemistry/metabolismCarbohydrates/ analysisChromatography/methodsGlycoproteins/ chemistry/metabolismGlycosylationPlasmodium falciparum/ chemistry/metabolismPrecipitin TestsProtozoan Proteins/ chemistry/metabolism
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PMID: 9352084
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