Metabolic labelling of Plasmodium falciparum parasites with [H-3]GlcN, [H-3]Man, [H-3]Gal and [H-3]ethanolamine, and subsequent purification by SDS-PAGE of the labelled material provided effective labelling of the MSP-1 195 kDe, 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 soduim hydroxide-sodium borotritideborohydride 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 glycoprotin using [H-3]UDP-Gal and galactosyltransferase. The galacosylated 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. Mannosamine inhibits biosynthesis as well as parasitemia of P.facliparum.
DANIEL C HOESSLI ,NASIR UD DIN ,ABBAS H KHAN ,
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