Diagnostic ions for the rapid analysis by nano-electrospray ionization quadrupole time-of-flight mass spectrometry of O-glycans from human mucins (original) (raw)
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ELECTROPHORESIS, 2003
The total glycan moiety was released in a single step from native glycoproteins by a nonreductive b-elimination procedure. The generated oligosaccharides were further derivatized either with the hydrophobic fluorophore 2-aminoacridone (AMAC) or the charged 8-aminonaphthalene-1,3,6-trisulfonic acid (ANTS) fluorophore, and the resulting fluorescent derivatives were separated according to their hydrodynamic size or charge with high-resolution gel electrophoresis. Both N-and O-glycans released by this b-elimination procedure might be analyzed simultaneously. AMAC derivatization allows a rapid separation of neutral and charged oligosaccharides without prior fractionation. Derivatized oligosaccharide species were then eluted from the gel slices and analyzed by mass spectrometry. This methodology allowed the rapid structural characterization of each glycan in term of monosaccharide composition and sequence. Using this technique we were able to screen several heterogeneous O-glycan mixtures isolated at the picomolar range from reference glycoproteins or mucins.
Biochemical Journal, 2004
Purified human mucins from different parts of the intestinal tract (ileum, cecum, transverse and sigmoid colon and rectum) were isolated from two individuals with blood group ALe b (A-Lewis b ). After alkaline borohydride treatment the released oligosaccharides were structurally characterized by nano-ESI Q-TOF MS/MS (electrospray ionization quadrupole time-of-flight tandem MS) without prior fractionation or derivatization. More than 100 different oligosaccharides, with up to ten monosaccharide residues, were identified using this technique. Oligosaccharides based on core 3 structures, GlcNAc(β1-3)GalNAc (where GlcNAc is N-acetyl-D-glucosamine and GalNAc is N-acetylgalactosamine), were widely distributed in human intestinal mucins. Core 5 structures, GalNAc(α1-3)GalNAc, were also recovered in all fractions. Moreover, a comparison of the oligosaccharide repertoire, with respect to size, diversity and expression of glycans and terminal epitopes, showed a high level of mucin-specific glycosyl-ation: highly fucosylated glycans, found specifically in the small intestine, were mainly based on core 4 structures, GlcNAc-(β1-3)[GlcNAc(β1-6)]GalNAc, whereas the sulpho-Le X determinant carrying core 2 glycans, Gal(β1-3)[GlcNAc(β1-6)]-GalNAc (where Gal is galactose), was recovered mainly in the distal colon. Blood group H and A antigenic determinants were present exclusively in the ileum and cecum, whereas blood group Sd a /Cad related epitopes, GalNAc(β1-4)[NeuAc(α2-3)]Gal (where NeuAc is N-acetylneuraminate), were found to increase along the length of the colon. Our findings suggest that mucins create an enormous repertoire of potential binding sites for microorganisms that could explain the regio-specific colonization of bacteria in the human intestinal tract.
ELECTROPHORESIS, 2004
A novel approach in glycosaminoglycomics, based on sheathless on-line capillary electrophoresis/nanoelectrospray ionization-quadrupole time of flight-mass spectrometry (CE/nanoESI-QTOF-MS) and tandem MS of extended chondroitin sulfate/ dermatan (CS/DS) oligosaccharide chains is described. The methodology required the construction of a new sheathless CE/nanoESI-QTOF-MS configuration, its implementation and optimization for the high sensitivity analysis of CS/DS oligosaccharide mixtures from conditioned culture medium of decorin transfected human embryonic kidney (HEK) 293 cells. Under newly established sheathless on-line CE/(-)nanoESI conditions for glycosaminoglycan (GAG) ionization and MS detection, single CS/DS oligosaccharide components of extended chain length and increased sulfation degree were identified. Molecular ions corresponding to species carrying 5 and 6 negative charges could be generated for large GAG oligosaccharide species in the negative ion nanoESI-MS. The optimized on-line conditions enabled the detection of molecular ions assigned to oversulfated tetradeca-, octadeca-, and eicosasaccharide CS/DS molecules, which represent the category of largest sulfated GAG-derived oligosaccharides evidenced by CE/ESI-MS. By on-line CE/ESI tandem MS in data-dependent acquisition mode the oversulfated eicosasaccharide species could be sequenced and the localization of the additional sulfate group along the chain could be determined.
Journal of the American Society for Mass Spectrometry, 2004
Neutral O-linked oligosaccharides released from the salivary mucin MUC5B were separated and detected by negative ion LC-MS and LC-MS 2 . The resolution of the chromatography and the information obtained from collision induced dissociation of detected [M Ϫ H] Ϫ ions were usually sufficient to identify the sequence of individual oligosaccharides, illustrated by the fact that 50 different oligosaccharides ranging from disaccharides to nonasaccharides could be assigned from the sample. Fragmentation was shown to yield mostly reducing end sequence fragments (Z i and Y i ), enabling primary sequence assignment. Specific fragmentation pathways or patterns were also detected giving specific linkage information. The reducing end core (Gal/GlcNAc1-3GalNAcol or Gal/GlcNAc1-3(GlcNAc1-6)GalNAcol) could be deduced from the pronounced glycosidic C-3 cleavage and A i type cleavages of the reducing end GalNAcol, together with the non reducing end fragment from the loss of a single substituted GalNAcol. Substitution patterns on GlcNAc residues were also found, indicative for C-4 substitution ( 0,2 A i Ϫ H 2 O cleavage) and disubstitution of C-3 and C-4 (Z i /Z i cleavages). This kind of fragmentation can be used for assigning the mode of chain elongation (Gal1-3/ 4GlcNAc1-) and identification of Lewis type antigens like Lewis a/x and Lewis b/y on O-linked oligosaccharides. In essence, negative ion LC-MS 2 was able to generate extensive data for understanding the overall glycosylation pattern of a sample, especially when only a limited amount of material is available. (J Am Soc Mass Spectrom 2004, 15, 659 -672)
Ion-spray mass spectrometric analysis of glycosaminoglycan oligosaccharides
Glycoconjugate Journal, 1992
Oligosaccharides from hyaluronic acid and chondroitin 6-sulfate were prepared by digestion with testicular hyaluronidase and separated according to their degree of polymerization by gel-permeation chromatography. These materials were successively analyzed by negative-mode ion-spray mass spectrometry with an atmospheric-pressure ion source. An ion-spray interface was used to produce ions via the ion evaporation process, producing mass spectra containing a series of molecular species carrying multiple charges. Using two adjacent multiply charged molecular ions, the exact molecular weights up to the tetradecasaccharide were calculated with a precision of +__ 1 dalton. This type of mass spectrometry was also demonstrated to be feasible for the analysis of mixtures of oligosaccharides, including tetra-, hexa-, octa-and decasaccharides, from hyaluronic acid or chondroitin 6-sulfate without separation. Ion-spray mass spectrometry was thus shown to be applicable to the structural analysis of oligosaccharides from glycosaminoglycans.
PROTEOMICS, 2009
Protein glycosylation involves the addition of monosaccharides in a stepwise process requiring no glycan template. Therefore, identifying the numerous glycoforms, including isomers, can help elucidate the biological function(s) of particular glycans. A method to assess the diversity of the N-linked oligosaccharides released from human serum without derivatization has been developed using on-line nano-liquid chromatography (nanoLC) and high resolution time-of-flight mass spectrometry. The N-linked oligosaccharides were analyzed with matrix-assisted laser desorption/ ionization Fourier transform ion cyclotron resonance mass spectrometry (MALDI FT-ICR MS) and microchip liquid chromatography mass spectrometry (HPLC-Chip/TOF MS). Two microfluidic chips were employed, the glycan chip (40 nL enrichment column, 43×0.075 mm ID analytical column) and the high capacity chip (160 nL enrichment column, 140×0.075 mm ID analytical column), both with graphitized carbon as the stationary phase. Both chips offered good sensitivity and reproducibility in separating a heterogeneous mixture of neutral and anionic oligosaccharides between injections. Increasing the length and volume of the enrichment and the analytical columns improved resolution of the peaks. Complex type N-linked oligosaccharides were the most abundant oligosaccharides in human serum accounting for ~96% of the total glycans identified, while hybrid and high mannose type oligosaccharides comprise the remaining 4%.
Oligosaccharides and Glycan Separation via Capillary Electrophoresis Coupled with Mass Spectroscopy
journal of chemistry and chemical engineering, 2021
After 2014, capillary electrophoresis (Fig. 1) has become an efficient method for carbohydrate evaluation. The methodology features a large resolution capable of distinguishing carbohydrates by the ratio of charge to scale. These primary features heavily focus on N-glycans, which seem to be extremely relevant for biological therapeutics and biomarker researches. Innovations in tools used during molecular or structural recognition of N-glycan involve time-indexing of migration and lectin profiling, also exoglycosidase along with mass spectrometry. Techniques of capillary electrophoresis have been formed that are able to separate glycans with the same sequence of simple sugars similar to other instruments but it can detect different positional isomers, and also specify whether alpha or beta is linked to monosaccharides comprising glycans. Based on the significant accomplishments of capillary electrophoresis to glycoscience from 2014 to the present, as addressed in this study, groundbreaking, evolving techniques in the field are highlighted and the potential direction of the technique is predicted. Fig. 1 Capillary electrophoresis working simple visual representation.
Analytical Chemistry, 2010
Appropriate glycosylation of recombinant therapeutic glycoproteins has been emphasized in biopharmaceutical industries because the carbohydrate component can affect safety, efficacy, and consistency of the glycoproteins. Reliable quantification methods are essential to ensure consistency of their products with respect to glycosylation, particularly sialylation. Mass spectrometry (MS) has become a popular tool to analyze glycan profiles and structures, showing high resolution and sensitivity with structure identification ability. However, quantification of sialylated glycans using MS is not as reliable because of the different ionization efficiency between neutral and acidic glycans. We report here that amidation in mild acidic conditions can be used to neutralize acidic N-glycans still attached to the protein. The resulting amidated N-glycans can then released from the protein using PNGase F, and labeled with permanent charges on the reducing end to avoid any modification and the formation of metal adducts during MS analysis. The N-glycan modification, digestion, and desalting steps were performed using a single-pot method that can be done in microcentrifuge tubes or 96-well microfilter plates, enabling high throughput glycan analysis. Using this method we were able to perform quantitative MALDI-TOF MS of a recombinant human glycoprotein to determine changes in fucosylation and changes in sialylation that were in very good agreement with a normal phase HPLC oligosaccharide mapping method.
Analytical chemistry, 2016
To characterize the structures of N-glycans derived from human serum, we report a strategy that combines microchip electrophoresis, standard addition, enzymatic digestion, and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). We compared: (i) electrophoretic mobilities of known N-glycans from well-characterized (standard) glycoproteins through standard addition, (ii) the electrophoretic mobilities of N-glycans with their molecular weights determined by MALDI-MS, and (iii) electrophoretic profiles of N-glycans enzymatically treated with fucosidase. The key step to identify the sialylated N-glycans was to quantitatively neutralize the negative charge on both α2,3- and α2,6-linked sialic acids by covalent derivatization with methylamine. Both neutralized and nonsialylated N-glycans from these samples were then reacted with 8-aminopyrene-1,3,6-trisulfonic acid (APTS) to provide a fluorescent label and a triple-negative charge, separated by microchip electrophores...