Comprehensive analysis of α 2-3-linked sialic acid specific Maackia amurensis leukagglutinin reveals differentially occupied N-glycans and C-terminal processing

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• 作者：Gnanesh Kumar B.S ; Avadhesha Surolia ; ^{surolia@mbu.iisc.ernet.in}
• 关键词：C-terminal processing ; Legume lectin ; Macroheterogeneity
• 刊名：International Journal of Biological Macromolecules
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：94
• 期：part_PA
• 页码：114-121
• 全文大小：794 K
• 卷排序：94

文摘

Seeds of Maackia amurensis constitutes two sialic acid specific agglutinins known as leukagglutinin and hemagglutinin. Maackia amurensis leukagglutinin (MAL) recognizes α2-3-linked sialic acid present mainly in N-glycans and composed of two disulfide linked monomers. It exhibits potential N-glycosylation sites (four PNGs) which have been assumed to undergo differential occupancy. In this study we have characterized the site specific macro- and microheterogeneity of monomers in detail by analysing N-glycopeptides and peptides through liquid chromatography coupled to ion trap mass spectrometer in MS3 mode (LC–MSn). We observed the presence of mainly paucimannose N-glycans at Asn61, Asn113 and Asn191 whereas a high mannose type with varying Man5–9 occurs at Asn179. Interestingly Asn179 and Asn191 exhibited differential occupancy which was evident by the presence of non-glycosylated peptides. This has contributed to the difference in molecular mass of monomers upon SDS-PAGE. Further the presence of disulfide linked peptides confirmed the covalent linkage of monomers which also undergoes uniform C-terminal processing.