earticle

영어

Maackia amurensis leukoagglutinin (MAL) is a glycoprotein and sialic acid-binding lectin that is used widely in the detection and characterization of sialoglycoconjugates and human cancer cells. However, its N-linked glycan structure and role have yet to be determined. The N-linked glycans were analyzed using high-performance liquid chromatography with matrix assisted laser desorption/ionization time-of-flight mass spectrometry, and the secondary structure was investigated using circular dichroismanalysis. A hemagglutination assay was performed. Furthermore, surface plasmon resonance analysis, and fluorescence microscopy and fluorescence-activated cell-sorting analysiswere conducted to assess the sialoglycoprotein-binding ability and its usefulness in the detection of human breast cancer MCF-7 cells, respectively. Analysis of the N-linked glycan structure ofMAL confirmed the presence of eight glycans, comprising two α1,3-fucosylated paucimannosidic-type and six high-mannose-type glycans. Glycan analysis of MAL that had been treated with peptide N-glycosidase F (de-M-MAL) revealed that while the two α1,3-fucosylated paucimannosidic glycans remained attached following the treatment, the six high-mannose-type glycans had been completely cleaved from the original MAL. There were almost no secondary structural changes between MAL and de-M-MAL; however, the lectin activities exhibited by MAL, such as hemagglutination and binding to a sialoglycoprotein, were completely absent in de-M-MAL, and the ability to detect human breast cancer MCF-7 cells was 77% lower in de-M-MAL than in MAL. The high-mannose-type glycans in intact MAL are closely associated with its lectin activities. This is the first report of the N-linked glycan structure of MAL and the effect of high mannose-type glycans on lectin activities.