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Peng J, Patil SM, Keire DA, Chen K. Chemical Structure and Composition of Major Glycans Covalently Linked to Therapeutic Monoclonal Antibodies by Middle-Down Nuclear Magnetic Resonance. Anal Chem 2018; 90:11016-11024. [PMID: 30102512 DOI: 10.1021/acs.analchem.8b02637] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Glycosylation of monoclonal antibodies (mAbs) is a critical quality attribute that can impact mAb drug efficacy and safety. The mAb glycans are inherently heterogeneous in chemical structure and composition of monosaccharides. The established fluorescence or mass-spectrometry (MS) detection methods for glycosylation evaluation may require multiple steps of glycan cleavage or extensive digestion of the mAb, chemical labeling of the glycans, column separation and report the chemical identity of glycans indirectly through retention time and molecular weight values. In demonstrating chemical structure similarity and comparability among mAb drugs, orthogonal analytical methods for measuring glycan chemistry are needed to ensure the quality of drug products. Here, a "middle-down" NMR method is developed as a proof-of-concept approach to measure the domain-specific glycosylation of marketed mAb drugs without cleavage of the glycan moieties. Complete glycan 1H/13C chemical shift assignments were obtained at 13C natural abundance from commercial standard glycans that allowed unambiguous determination of the chemical structure, glycosidic linkage position, and anomeric configuration of each monosaccharide in the major N-glycan scaffolds found in mAb molecules. The analysis of glycan anomeric peaks in two-dimensional (2D) 1H-13C NMR spectra yielded metrics for clinically important mAb quality attributes (i.e., galactosylation (Gal%) and fucosylation (Fuc%)), consistent with literature results using a standard glycan-mapping method. Therefore, the middle-down NMR method provided a facile orthogonal measurement for mAb glycosylation characterization with improved chemical information content on glycan structure determination and quantification, compared to standard approaches.
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2
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Schubert M, Walczak MJ, Aebi M, Wider G. Posttranslational Modifications of Intact Proteins Detected by NMR Spectroscopy: Application to Glycosylation. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201502093] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Schubert M, Walczak MJ, Aebi M, Wider G. Posttranslational modifications of intact proteins detected by NMR spectroscopy: application to glycosylation. Angew Chem Int Ed Engl 2015; 54:7096-100. [PMID: 25924827 DOI: 10.1002/anie.201502093] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Indexed: 02/02/2023]
Abstract
Posttranslational modifications (PTMs) are an integral part of the majority of proteins. The characterization of structure and function of PTMs can be very challenging especially for glycans. Existing methods to analyze PTMs require complicated sample preparations and suffer from missing certain modifications, the inability to identify linkage types and thus chemical structure. We present a direct, robust, and simple NMR spectroscopy method for the detection and identification of PTMs in proteins. No isotope labeling is required, nor does the molecular weight of the studied protein limit the application. The method can directly detect modifications on intact proteins without sophisticated sample preparation. This approach is well suited for diagnostics of proteins derived from native organisms and for the quality control of biotechnologically produced therapeutic proteins.
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Affiliation(s)
- Mario Schubert
- Institute of Molecular Biology and Biophysics, ETH Zürich, 8093 Zürich (Switzerland). .,Present address: Department of Molecular Biology, University of Salzburg, Billrothstrasse 11, 5020 Salzburg (Austria).
| | - Michal J Walczak
- Institute of Molecular Biology and Biophysics, ETH Zürich, 8093 Zürich (Switzerland).
| | - Markus Aebi
- Institute of Microbiology, ETH Zürich, 8093 Zürich (Switzerland)
| | - Gerhard Wider
- Institute of Molecular Biology and Biophysics, ETH Zürich, 8093 Zürich (Switzerland)
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NMR analysis demonstrates immunoglobulin G N-glycans are accessible and dynamic. Nat Chem Biol 2011; 7:147-53. [PMID: 21258329 PMCID: PMC3074608 DOI: 10.1038/nchembio.511] [Citation(s) in RCA: 139] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Accepted: 08/04/2010] [Indexed: 11/08/2022]
Abstract
The N-glycan at Asn297 of the immunoglobulin G Fc fragment modulates cellular responses of the adaptive immune system. However, the underlying mechanism remains undefined, as existing structural data suggest the glycan does not directly engage cell surface receptors. Here we characterize the dynamics of the glycan termini using solution NMR spectroscopy. Contrary to previous conclusions based on X-ray crystallography and limited NMR data, our spin relaxation studies indicate that the termini of both glycan branches are highly dynamic and experience considerable motion in addition to tumbling of the Fc molecule. Relaxation dispersion and temperature-dependent chemical shift perturbations demonstrate exchange of the α1-6Man-linked branch between a protein-bound and a previously unobserved unbound state, suggesting the glycan samples conformational states that can be accessed by glycan-modifying enzymes and possibly glycan recognition domains. These findings suggest a role for Fc-glycan dynamics in Fc-receptor interactions and enzymatic glycan remodeling.
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Barb AW, Brady EK, Prestegard JH. Branch-specific sialylation of IgG-Fc glycans by ST6Gal-I. Biochemistry 2009; 48:9705-7. [PMID: 19772356 DOI: 10.1021/bi901430h] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Sialylated forms of the Fc fragment of immunoglobulin G, produced by the human alpha2-6 sialyltransferase ST6Gal-I, were identified as potent anti-inflammatory mediators in a mouse model of rheumatoid arthritis and are potentially the active components in intravenous IgG anti-inflammatory therapies. The activities and specificities of hST6Gal-I are, however, poorly characterized. Here MS and NMR methodology demonstrates glycan modification occurs in a branch-specific manner with the alpha1-3Man branch of the complex, biantennary Fc glycan preferentially sialylated. Interestingly, this substrate preference is preserved when using a released glycan, suggesting that the apparent occlusion of glycan termini in Fc crystal structures does not dominate specificity.
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Affiliation(s)
- Adam W Barb
- Complex Carbohydrate Research Center, 315 Riverbend Road, University of Georgia, Athens, Georgia 30602, USA
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Lu J, van Halbeek H. Complete 1H and 13C resonance assignments of a 21-amino acid glycopeptide prepared from human serum transferrin. Carbohydr Res 1996; 296:1-21. [PMID: 9008840 DOI: 10.1016/s0008-6215(96)00240-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A 21-amino acid glycopeptide (Gp21) was isolated and purified in multi-milligram yields from commercially available human serum transferrin (HSTF) by a combination of tryptic digestion, Con A affinity chromatography, and reverse phase HPLC. The peptide chain of Gp21 contains a single N-glycosylation site to which a diantennary oligosaccharide is attached. The amino acid sequence and the glycan primary structure of Gp21 have been verified by peptide sequencing, electrospray mass spectrometry, and one-dimensional 1H NMR spectroscopy. Different glycoforms were found for the glycan of Gp21 derived from two different batches of commercial HSTF. These glycoforms differ from one another in the number of NeuAc residues (ranging from 0 to 2) and/or the number of Gal residues (ranging from 1 to 2). As for the monogalacto species, in the two-dimensional nuclear Overhauser effect (NOE) spectrum of Gp21, interglycosidic NOEs were observed between Man4 in the alpha (1-->3) branch and the terminal GlcNAc beta (1-->2) residue. No interglycosidic NOE was observed between Man4' in the alpha (1-->6) branch and the terminal GlcNAc residue. These observations indicate that the terminal GlcNAc residue in the minor glycoforms of Gp21 is exclusively located in the alpha (1-->3) branch of the Gp21 glycan. The occurrence of such a carbohydrate structure in HSTF has not been reported before. The 1H and 13C NMR spectra of Gp21 have been completely assigned by two-dimensional homonuclear and heteronuclear spectroscopy. The close similarity of the 1H and 13C chemical shift values for the Gp21 glycan with the respective values for the peptide-free diantennary oligosaccharide (Wieruszeski et al., Glycoconjugate J., 6 (1989) 183-194) indicates that the 1H and 13C chemical shifts of the diantennary oligosaccharide are not perturbed by the presence of the Gp21 peptide fragment. The complete 1H and 13C resonance assignments and the full characterization of the primary structure of Gp21 will permit us to study the conformation and dynamics of the N-linked diantennary oligosaccharides while covalently attached to a polypeptide fragment.
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Affiliation(s)
- J Lu
- Complex Carbohydrate Research Center, University of Georgia, Athens 30602-4712, USA
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De Beer T, Van Zuylen CW, Leeflang BR, Hård K, Boelens R, Kaptein R, Kamerling JP, Vliegenthart JF. NMR studies of the free alpha subunit of human chorionic gonadotropin. Structural influences of N-glycosylation and the beta subunit on the conformation of the alpha subunit. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 241:229-42. [PMID: 8898911 DOI: 10.1111/j.1432-1033.1996.0229t.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Human chorionic gonadotropin (hCG) is a heterodimeric glycoprotein hormone that is involved in the maintenance of the corpus luteum in early pregnancy. Glycosylation at Asn52 of its alpha subunit (alpha hCG) is essential for signal transduction, whereas the N-glycan at Asn78 stabilizes the structure of the protein. In this study, an almost complete 1H-NMR and a partial 13C-NMR spectral assignment for the amino acids and the N-glycans of alpha hCG and of an enzymatically deglycosylated form, which had a single GlcNAc residue at each of its two glycosylation sites, has been achieved. The secondary structure of alpha hCG is solution, which was determined based on NOE data, is partially similar to that of the alpha subunit in the crystal structure of hCG, but large structural differences are found for amino acid residues 33-58. In the crystal structure of hCG, residues 33-37 and 54-58 of the alpha subunit are part of an intersubunit seven-stranded beta-barrel and residues 41-47 constitute a 3(10)-helix. In contrast, in free alpha hCG in solution, amino acids 33-58 are part of a large disordered loop, indicating that in intact hCG interactions with the beta subunit of hCG stabilize the conformation of the alpha subunit. The NMR data of alpha hCG and its deglycosylated counterpart are very similar, indicating that removal of carbohydrate residues other than GlcNAc-1 does not notably affect the conformation of the protein part. However, numerous 1H-NOEs between the GlcNAc-1 residue at Asn78 and several amino acid residues show that this GlcNAc residue is tightly packed against the protein, being an integral part of the structure of the alpha subunit. 1H-NOEs across the glycosidic linkages of the glycan, resonance-line widths, and 1H and 13C chemical shifts of the other monosaccharides suggest that the remainder of the glycans at Asn78, and the glycans at Asn52 are largely extended in solution.
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Affiliation(s)
- T De Beer
- Department of Bio-Organic Chemistry, Bijvoet Center, Utrecht University, The Netherlands
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8
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Helin J, Maaheimo H, Seppo A, Keane A, Renkonen O. Stepwise transfer of alpha-D-Galp-(1-->3)-beta-D-Galp-(1-->4)-beta-D-GlcpNAc sequences to 3-OH and 6-OH of distal galactose residues in bi-, tri-, and tetra-antennary asialo-glycans of N-linked complex type. Carbohydr Res 1995; 266:191-209. [PMID: 7697655 DOI: 10.1016/0008-6215(94)00272-h] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The hydroxyl groups 3 and 6 of distal galactose units in bi-, tri-, and tetra-antennary asialo-glycans of N-linked complex type were substituted stepwise by transferase reactions with the sequence alpha-D-Galp-(1-->3)-beta-D-Galp-(1-->4)-beta-D-GlcpNAc. The products of each transferase reaction were purified chromatographically and the structures were confirmed by 1H NMR spectroscopy. Molecular weights of the final products were determined by matrix-assisted laser-desorption mass spectrometry (MALDI-MS).
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Affiliation(s)
- J Helin
- Institute of Biotechnology, University of Helsinki, Finland
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de Beer T, van Zuylen CW, Hård K, Boelens R, Kaptein R, Kamerling JP, Vliegenthart JF. Rapid and simple approach for the NMR resonance assignment of the carbohydrate chains of an intact glycoprotein. Application of gradient-enhanced natural abundance 1H-13C HSQC and HSQC-TOCSY to the alpha-subunit of human chorionic gonadotropin. FEBS Lett 1994; 348:1-6. [PMID: 8026573 DOI: 10.1016/0014-5793(94)00547-8] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The structure assessment of an intact glycoprotein in solution requires an extensive assignment of the carbohydrate NMR resonances. However, assignment of homonuclear spectra is very complicated because of the severe overlap of protein and carbohydrate signals. Application of pulsed field gradients allowed high quality natural abundance 1H-13C HSQC and HSQC-TOCSY spectra to be recorded of the alpha-subunit of human chorionic gonadotropin. Most carbohydrate 1H-13C correlations appear in a distinct region between the aromatic region and the protein C alpha-H alpha region. The enormous reduction in overlap led to fast and unambiguous assignment of the anomeric 1H-13C correlations. Subsequently, correlations of the monosaccharide skeleton atoms were readily assigned in the HSQC-TOCSY spectrum.
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Affiliation(s)
- T de Beer
- Department of Bio-Organic Chemistry, Utrecht University, The Netherlands
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Harris RJ, van Halbeek H, Glushka J, Basa LJ, Ling VT, Smith KJ, Spellman MW. Identification and structural analysis of the tetrasaccharide NeuAc alpha(2-->6)Gal beta(1-->4)GlcNAc beta(1-->3)Fuc alpha 1-->O-linked to serine 61 of human factor IX. Biochemistry 1993; 32:6539-47. [PMID: 8329384 DOI: 10.1021/bi00077a007] [Citation(s) in RCA: 89] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
O-Linked fucose has been found attached to Thr/Ser residues within the sequence Cys-X-X-Gly-Gly-Thr/Ser-Cys in the N-terminal EGF domains of several coagulation/fibrinolytic proteins. Carbohydrate composition and mass spectrometric analyses of tryptic and thermolytic peptides containing the corresponding site (Ser-61) in the first EGF domain of human factor IX indicated the presence of a tetrasaccharide containing one residue each of sialic acid, galactose, N-acetylglucosamine, and fucose. The Ser-61 tetrasaccharide was not susceptible to alpha-fucosidase digestion. Fragments generated during mass spectrometric analysis indicated that fucose was the attachment sugar residue. The involvement of fucose in the carbohydrate-peptide linkage was confirmed by two-dimensional 1H NMR spectroscopic analysis of the glycopeptide containing factor IX residues 57-65. The complete structure of the tetrasaccharide was obtained by methylation analysis and two-dimensional 1H TOCSY and ROESY experiments as NeuAc alpha(2-->6)Gal beta(1-->4)GlcNAc beta(1-->3)Fuc alpha 1-->O-Ser61.
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Affiliation(s)
- R J Harris
- Department of Medicinal and Analytical Chemistry, Genentech, Inc., South San Francisco, California 94080
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Hård K, Spronk BA, Hokke CH, Kamerling JP, Vliegenthart JF. The potency of amide protons for assignments of NMR spectra of carbohydrate chains of glycoproteins, recorded in 1H2O solutions. FEBS Lett 1991; 287:108-12. [PMID: 1879518 DOI: 10.1016/0014-5793(91)80027-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Three glycoprotein N-glycans, namely, a disialylated diantennary carbohydrate chain linked to Asn, a monosialylated, fucosylated diantennary glycopeptide with bisecting N-acetylglucosamine, and a tetrasialylated, fucosylated tetra-antennary oligosaccharide, have been investigated by two-dimensional NOE and HOHAHA spectroscopy in 1H2O as solvent. The amide protons of all N-acetylglucosamine and sialic acid residues could readily be assigned. The large chemical-shift dispersion of the amide resonances of the N-acetylglucosamine residues, allowed the unambiguous assignment of every N-acetyl methyl signal, via strong NOEs. Subspectra could be obtained of all N-acetylglucosamine residues in HOHAHA spectra. These results have as main implication that several biologically important large glycans will now [corrected] become amenable for conformational studies by multidimensional NMR in 1H2O solution.
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Affiliation(s)
- K Hård
- Bijvoet Center, Department of Bio-Organic Chemistry, Utrecht University, The Netherlands
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Weisshaar G, Hiyama J, Renwick AG. Site-specific N-glycosylation of ovine lutropin. Structural analysis by one- and two-dimensional 1H-NMR spectroscopy. EUROPEAN JOURNAL OF BIOCHEMISTRY 1990; 192:741-51. [PMID: 2209620 DOI: 10.1111/j.1432-1033.1990.tb19285.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The Asn-linked carbohydrate structures of the heterodimeric glycoprotein hormone lutropin from ovine pituitary glands have been investigated at each of its three glycosylation sites using one- and two-dimensional 400-MHz 1H-NMR spectroscopy. Highly purified, biologically active ovine lutropin (oLH) was dissociated and separated into its alpha and beta subunits (oLH alpha, glycosylated at Asn56 and Asn82; oLH beta glycosylated at Asn13). Oligosaccharides from intact oLH beta and from glycopeptides obtained after tryptic digestion of oLH alpha were released by hydrazinolysis and subsequently fractionated according to charge and size by anion-exchange and ion-suppression amine-adsorption HPLC, respectively. 1H-NMR analysis revealed, that monosulphated, mostly hybrid-type, oligosaccharides predominate at both glycosylation sites of oLH alpha, whereas a disulphated, diantennary N-acetyllactosamine-type structure accounts for more than 60% of total oligosaccharides in the beta subunit. Furthermore, the saccharides attached to the beta subunit are almost completely fucosylated (Fuc alpha 1-6) at the reducing terminal GlcNAc, whereas the sugar chains in oLH alpha are either approximately 50% fucosylated (Asn82) or contain fucose only to a minor extent (Asn56). The results clearly indicate a distinct subunit- and site-specific synthesis of oligosaccharides in ovine lutropin and suggest that biosynthesis is effectively influenced by the surrounding polypeptide chain(s) at a given site.
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Affiliation(s)
- G Weisshaar
- Department of Biochemistry, University of Auckland, New Zealand
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