PubMed · 8018306
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P F Luckham, P G Hartley. 1994-04-29. Interactions between biosurfaces.. https://doi.org/10.1016/0001-8686(94)80019-7
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Collision-induced dissociation (CID) is used in an external source Fourier transform mass spectrometer (FTMS) equipped with matrix-assisted laser desorption/ionization (MALDI) to study a number of complex, branched oligosaccharides. The relative dissociation thresholds for various oligosaccharide fragmentation pathways have been calculated in terms of kinetic and center-of-mass frame energy. For two isomers of difucosyllacto-N-hexaose, the loss of the fucose sugar is always the lowest energy fragment observed and occurs at the same energy for both isomers when the oligosaccharide is coordinated to a sodium ion. When the oligosaccharide is complexed to cesium, the threshold for the removal of the fucose moiety increases, indicating that the cesium is involved in a coordination complex that stabilizes the sugar. MS/ MS/MS is performed on a sugar, mannose core, which does not readily fragment during MALDI. In all the sugars examined, CID produces additional structural information relative to MALDI/FTMS.
Studies on the structures and binding properties of the glycoproteins, purified from human ovarian cyst fluids, will aid the understanding of the carbohydrate alterations occurring during the biosynthesis of blood group antigens and neoplasm formation. These glycoproteins can also serve as important biological materials to study blood group A, B, H, Le(a), Le(b), Le(x), Le(y), T and Tn determinants, precursor type I and II sequences and cold agglutinin I and i epitopes. In this study, the binding property of a cyst glycoprotein from a human blood group Le(a+) nonsecretor individual, that contains an unusually high amount (18%) of sialic acid (HOC 350) was characterized by quantitative precipitin assay with a panel of lectins exhibiting a broad range of carbohydrate-binding specificities. Native HOC 350 reacted well only with three out of nineteen lectins tested. It precipitated about 80% of Ricinus communis (RCA1), 50% of Triticum vulgaris (WGA) and 37% of Bauhinia purpurea aba (BPA) agglutinins, respectively. However, its asialo product had dramatically enhanced reactivity and reacted well with many I/II (Gal beta1 --> 3/4GcNAc), T(Gal beta1 --> 3GalNAc) and Tn(GaNIAc alphaI --> Ser/Thr) active lectins. It bound best to Jacalin, BPA, and abrin-a and completely precipitated all the lectins added. Asialo-HOC 350 also reacted strongly with Wistaria floribunda, Abrus precatorius agglutinin, ricin and RCA1 and precipitated over 75% of the lectin nitrogen added, and moderately with Arachis hypogaea, Maclura pomifera, WGA, Vicia viosa-B4, Codium fragile tomentosoides and Ulex europaeus-II. But native HOC 350 and its asialo product reacted not at all or poorly with Dolichos biflorus, Helix pomatia, Lotus tetra-gonolobus, Ulex europaeus-I, Lens culinaris lectins and Con A. The lectin-glycoform interactions through bioactive sugars were confirmed by precipitin inhibition assay. Mapping the precipitation profiles of the interactions have led to the conclusion that HOC 350 contains a large number of receptors for I/II, T, and Tn active lectins. But in the untreated (or native) substance, most of these determinants are masked by sialic acids.
Mycobacterium "habana" strain TMC 5135, which has been proposed as a vaccine against both leprosy and tuberculosis, is considered to be a strain of serotype I of the recognized species Mycobacterium simiae. We have now shown that each of these strains possesses characteristic polar glycopeptidolipids (GPL) which are sufficiently different to allow unequivocal strain identification. Thin layer chromatographic analysis demonstrated that M. habana synthesizes a family of apolar GPLs and three distinct polar GPLs (pGPL-I to -III) which exhibited migration patterns different from those of M. simiae serotype I (pGPL-Sim). Using a combination of chemical, mass spectrometric, and proton-NMR analyses, the GPLs from M. habana were determined to be based on the same generic structure as those from the M. avium complex, namely N-fatty acyl-D-Phe-(O-saccharide)-D-allo-Thr-D-Ala-L-alaninyl-O-m onosaccharide. The de-O-acetylated apolar GPLs contain a 3-O-Me-6-deoxy-Tal attached to the allo-Thr and either a 3-O-Me-Rha or a 3,4-di-O-Me-Rha attached to the alaninol. In the pGPLs, oligosaccharides were found to be attached to the allo-Thr. The oligoglycosyl alditol reductively released from the least polar pGPL-I was fully characterized as L-Fucp alpha 1 in --7 with 3-(6-O-Me)-D-Glcp beta 1 in --7 with 3-(4-O-Me)-L-Rhap alpha 1 in --7 with 3-L-Rhap alpha 1 in --7 with 2-(3-O-Me)-6-deoxy-Tal. In pGPl-II and -III, the terminal Fuc residue is further 3-O-methylated and 4-O-substituted with an additional 2,4-di-O-Me-D-GlcA and 4-O-Me-D-GlcA, respectively. The corresponding oligosaccharide from pGPL-Sim was shown to be of identical molecular weight to pGPL-II but terminating with a 3,4-di-O-Me-GlcA. Enzyme-linked immunosorbent assay-based serological studies using anti-M. habana and anti-M. simiae sera against whole cells and purified pGPLs firmly established the polar GPLs as important antigens and indicated that the terminal epitopes L-Fuc-, 2,4-di-O-Me-D-GlcA, and 4-O-Me-D-GlcA uniquely present in pGPL-I, -II, and -III, respectively, confer sufficient specificity for the identification of M. habana as a distinct serotype of M. simiae.