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D’Antona AM, Lee JM, Zhang M, Friedman C, He T, Mosyak L, Bennett E, Lin L, Silverman M, Cometa F, Meade C, Hageman T, Sousa E, Cohen J, Marquette K, Ferguson D, Zhong X. Tyrosine Sulfation at Antibody Light Chain CDR-1 Increases Binding Affinity and Neutralization Potency to Interleukine-4. Int J Mol Sci 2024; 25:1931. [PMID: 38339208 PMCID: PMC10855961 DOI: 10.3390/ijms25031931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 01/30/2024] [Accepted: 02/01/2024] [Indexed: 02/12/2024] Open
Abstract
Structure and function of therapeutic antibodies can be modulated by a variety of post-translational modifications (PTM). Tyrosine (Tyr) sulfation is a type of negatively charged PTM that occurs during protein trafficking through the Golgi. In this study, we discovered that an anti-interleukin (IL)-4 human IgG1, produced by transiently transfected HEK293 cells, contained a fraction of unusual negatively charged species. Interestingly, the isolated acidic species exhibited a two-fold higher affinity to IL-4 and a nearly four-fold higher potency compared to the main species. Mass spectrometry (MS) showed the isolated acidic species possessed an +80-Dalton from the expected mass, suggesting an occurrence of Tyr sulfation. Consistent with this hypothesis, we show the ability to control the acidic species during transient expression with the addition of Tyr sulfation inhibitor sodium chlorate or, conversely, enriched the acidic species from 30% to 92% of the total antibody protein when the IL-4 IgG was co-transfected with tyrosylprotein sulfotransferase genes. Further MS and mutagenesis analysis identified a Tyr residue at the light chain complementarity-determining region-1 (CDRL-1), which was sulfated specifically. These results together have demonstrated for the first time that Tyr sulfation at CDRL-1 could modulate antibody binding affinity and potency to a human immune cytokine.
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Affiliation(s)
- Aaron M. D’Antona
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Julie M. Lee
- Translational Clinical Sciences, Pfizer Discovery & Early Development, 610 Main Street, Cambridge, MA 02139, USA
| | - Melvin Zhang
- Inflammation and Immunology Research Unit, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA
| | - Clarence Friedman
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Tao He
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Lidia Mosyak
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Eric Bennett
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Laura Lin
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Maddison Silverman
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Funi Cometa
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Caryl Meade
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Tyler Hageman
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Eric Sousa
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Justin Cohen
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Kimberly Marquette
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Darren Ferguson
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
| | - Xiaotian Zhong
- BioMedicine Design, Pfizer Research & Development, 610 Main Street, Cambridge, MA 02139, USA (T.H.); (T.H.); (E.S.)
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2
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Hidayah SN, Biabani A, Gaikwad M, Nissen P, Voß H, Riedner M, Schlüter H, Siebels B. Application of sample displacement batch chromatography for fractionation of proteoforms. Proteomics 2024; 24:e2200424. [PMID: 37750450 DOI: 10.1002/pmic.202200424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 09/06/2023] [Accepted: 09/07/2023] [Indexed: 09/27/2023]
Abstract
Fractionation of proteoforms is currently the most challenging topic in the field of proteoform analysis. The need for considering the existence of proteoforms in experimental approaches is not only important in Life Science research in general but especially in the manufacturing of therapeutic proteins (TPs) like recombinant therapeutic antibodies (mAbs). Some of the proteoforms of TPs have significantly decreased actions or even cause side effects. The identification and removal of proteoforms differing from the main species, having the desired action, is challenging because the difference in the composition of atoms is often very small and their concentration in comparison to the main proteoform can be low. In this study, we demonstrate that sample displacement batch chromatography (SDBC) is an easy-to-handle, economical, and efficient method for fractionating proteoforms. As a model sample a commercial ovalbumin fraction was used, containing many ovalbumin proteoforms. The most promising parameters for the SDBC were determined by a screening approach and applied for a 10-segment fractionation of ovalbumin with cation exchange chromatography resins. Mass spectrometry of intact proteoforms was used for characterizing the SDBC fractionation process. By SDBC, a significant separation of different proteoforms was obtained.
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Affiliation(s)
- Siti Nurul Hidayah
- Section Mass Spectrometric Proteomics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Universitas Gadjah Mada, Sleman, Yogyakarta, Indonesia
| | - Ali Biabani
- Section Mass Spectrometric Proteomics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Manasi Gaikwad
- Section Mass Spectrometric Proteomics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Paula Nissen
- Section Mass Spectrometric Proteomics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Hannah Voß
- Section Mass Spectrometric Proteomics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Maria Riedner
- Technology Platform Mass Spectrometry, University of Hamburg, Hamburg, Germany
| | - Hartmut Schlüter
- Section Mass Spectrometric Proteomics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Bente Siebels
- Section Mass Spectrometric Proteomics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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3
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Luo H, Mahon D, Wong P, Madayiputhiya N, Chen Y, Stauffer T, Tao L, Zeng M. Structure-function relationship study for sulfated protein therapeutics using hydrophobic interaction chromatography and mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci 2024; 1233:123981. [PMID: 38184885 DOI: 10.1016/j.jchromb.2023.123981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 12/07/2023] [Accepted: 12/19/2023] [Indexed: 01/09/2024]
Abstract
Protein tyrosine sulfation is a post-translational modification (PTM) that is rarely reported in recombinant therapeutic proteins. However, when sulfation does occur, the additional negative charge from the modification can influence intermolecular interactions and antigen-binding activity, making it a critical quality attribute that necessitates stringent control. In this study, we developed a unique hydrophobic interaction chromatography (HIC) method for the separation and quantification of a therapeutic bispecific antibody with varying degrees of sulfation. Despite the increased surface hydrophilicity of sulfated species, the HIC method provides enhanced retention. Baseline resolution was attained based on the degree of sulfation, independent of other PTMs such as C-terminal amidation and forced deamidation. Further structure-function relationship studies of enriched sulfated bispecific antibody species were conducted using mass spectrometry and fluorescence-linked immunosorbent assay (FLISA). These studies revealed that the tyrosine sulfation modification, which occurs in the complementarity-determining region (CDR), is a critical quality attribute and can adversely impact the antibody's binding to its cognate antigen. The evaluation of sulfation assay using HIC method confirmed it is an effective means for controlling this critical quality attribute.
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Affiliation(s)
- Hao Luo
- Biologics Development, Global Product Development and Supply, Bristol Myers Squibb, NJ, USA.
| | - David Mahon
- Biologics Development, Global Product Development and Supply, Bristol Myers Squibb, NJ, USA
| | - Patrick Wong
- Biologics Development, Global Product Development and Supply, Bristol Myers Squibb, NJ, USA
| | | | - Yingchen Chen
- Biologics Development, Global Product Development and Supply, Bristol Myers Squibb, NJ, USA
| | - Tara Stauffer
- Biologics Development, Global Product Development and Supply, Bristol Myers Squibb, NJ, USA
| | - Li Tao
- Biologics Development, Global Product Development and Supply, Bristol Myers Squibb, NJ, USA
| | - Ming Zeng
- Biologics Development, Global Product Development and Supply, Bristol Myers Squibb, NJ, USA
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4
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Vitharana S, Stillahn JM, Katayama DS, Henry CS, Manning MC. Application of Formulation Principles to Stability Issues Encountered During Processing, Manufacturing, and Storage of Drug Substance and Drug Product Protein Therapeutics. J Pharm Sci 2023; 112:2724-2751. [PMID: 37572779 DOI: 10.1016/j.xphs.2023.08.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 07/24/2023] [Accepted: 08/07/2023] [Indexed: 08/14/2023]
Abstract
The field of formulation and stabilization of protein therapeutics has become rather extensive. However, most of the focus has been on stabilization of the final drug product. Yet, proteins experience stress and degradation through the manufacturing process, starting with fermentaition. This review describes how formulation principles can be applied to stabilize biopharmaceutical proteins during bioprocessing and manufacturing, considering each unit operation involved in prepration of the drug substance. In addition, the impact of the container on stabilty is discussed as well.
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Affiliation(s)
| | - Joshua M Stillahn
- Legacy BioDesign LLC, Johnstown, CO 80534, USA; Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA
| | | | - Charles S Henry
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA
| | - Mark Cornell Manning
- Legacy BioDesign LLC, Johnstown, CO 80534, USA; Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA.
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5
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Gunawardena HP, Jayatilake MM, Brelsford JD, Nanda H. Diagnostic utility of N-terminal TMPP labels for unambiguous identification of clipped sites in therapeutic proteins. Sci Rep 2023; 13:18602. [PMID: 37903854 PMCID: PMC10616084 DOI: 10.1038/s41598-023-45446-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 10/19/2023] [Indexed: 11/01/2023] Open
Abstract
Protein therapeutics are susceptible to clipping via enzymatic and nonenzymatic mechanisms that create neo-N-termini. Typically, neo-N-termini are identified by chemical derivatization of the N-terminal amine with (N-Succinimidyloxycarbonylmethyl)tris(2,4,6-trimethoxyphenyl)phosphonium bromide (TMPP) followed by proteolysis and mass spectrometric analysis. Detection of the TMPP-labeled peptide is achieved by mapping the peptide sequence to the product ion spectrum derived from collisional activation. The site-specific localization of the TMPP tag enables unambiguous determination of the true N-terminus or neo-N-termini. In addition to backbone product ions, TMPP reporter ions at m/z 573, formed via collision-induced dissociation, can be diagnostic for the presence of a processed N-termini. However, reporter ions generated by collision-induced dissociation may be uninformative because of their low abundance. We demonstrate a novel high-throughput LC-MS method for the facile generation of the TMPP reporter ion at m/z 533 and, in some instances m/z 590, upon electron transfer dissociation. We further demonstrate the diagnostic utility of TMPP labeled peptides derived from a total cell lysate shows high degree of specificity towards selective N-terminal labeling over labeling of lysine and tyrosine and highly-diagnostic Receiver Operating Characteristic's (ROC) of TMPP reporter ions of m/z 533 and m/z 590. The abundant generation of these reporters enables subsequent MS/MS by intensity and m/z-dependent triggering of complementary ion activation modes such as collision-induced dissociation, high-energy collision dissociation, or ultraviolet photo dissociation for subsequent peptide sequencing.
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Affiliation(s)
- Harsha P Gunawardena
- Janssen Research and Development LLC, The Janssen Pharmaceutical Companies of Johnson & Johnson, Spring House, PA, USA.
| | - Meth M Jayatilake
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington DC, USA
| | - Jeffery D Brelsford
- Janssen Research and Development LLC, The Janssen Pharmaceutical Companies of Johnson & Johnson, Spring House, PA, USA
| | - Hirsh Nanda
- Janssen Research and Development LLC, The Janssen Pharmaceutical Companies of Johnson & Johnson, Spring House, PA, USA
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6
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Spanov B, Baartmans B, Olaleye O, Nicolardi S, Govorukhina N, Wuhrer M, van de Merbel NC, Bischoff R. Revealing charge heterogeneity of stressed trastuzumab at the subunit level. Anal Bioanal Chem 2023; 415:1505-1513. [PMID: 36693954 PMCID: PMC9974696 DOI: 10.1007/s00216-023-04547-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 12/24/2022] [Accepted: 01/16/2023] [Indexed: 01/26/2023]
Abstract
Trastuzumab is known to be heterogeneous in terms of charge. Stressing trastuzumab under physiological conditions (pH 7.4 and 37 °C) increases charge heterogeneity further. Separation of charge variants of stressed trastuzumab at the intact protein level is challenging due to increasing complexity making it difficult to obtain pure charge variants for further characterization. Here we report an approach for revealing charge heterogeneity of stressed trastuzumab at the subunit level by pH gradient cation-exchange chromatography. Trastuzumab subunits were generated after limited proteolytic cleavage with papain, IdeS, and GingisKHAN®. The basic pI of Fab and F(ab)2 fragments allowed to use the same pH gradient for intact protein and subunit level analysis. Baseline separation of Fab subunits was obtained after GingisKHAN® and papain digestion and the corresponding modifications were determined by LC-MS/MS peptide mapping and middle-down MALDI-ISD FT-ICR MS. The described approach allows a comprehensive charge variant analysis of therapeutic antibodies that have two or more modification sites in the Fab region.
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Affiliation(s)
- Baubek Spanov
- Department of Analytical Biochemistry, Groningen Research Institute of Pharmacy, University of Groningen, A Deusinglaan 1, 9713 AV, Groningen, The Netherlands
| | - Bas Baartmans
- Department of Analytical Biochemistry, Groningen Research Institute of Pharmacy, University of Groningen, A Deusinglaan 1, 9713 AV, Groningen, The Netherlands
| | - Oladapo Olaleye
- Department of Analytical Biochemistry, Groningen Research Institute of Pharmacy, University of Groningen, A Deusinglaan 1, 9713 AV, Groningen, The Netherlands
| | - Simone Nicolardi
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA, Leiden, The Netherlands
| | - Natalia Govorukhina
- Department of Analytical Biochemistry, Groningen Research Institute of Pharmacy, University of Groningen, A Deusinglaan 1, 9713 AV, Groningen, The Netherlands
| | - Manfred Wuhrer
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA, Leiden, The Netherlands
| | - Nico C van de Merbel
- Department of Analytical Biochemistry, Groningen Research Institute of Pharmacy, University of Groningen, A Deusinglaan 1, 9713 AV, Groningen, The Netherlands.,Bioanalytical Laboratory, ICON, Amerikaweg 18, 9407 TK, Assen, The Netherlands
| | - Rainer Bischoff
- Department of Analytical Biochemistry, Groningen Research Institute of Pharmacy, University of Groningen, A Deusinglaan 1, 9713 AV, Groningen, The Netherlands.
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7
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Lietz CB, Deyanova E, Cho Y, Cordia J, Franc S, Kabro S, Wang S, Mikolon D, Banks DD. Identification of tyrosine sulfation in the variable region of a bispecific antibody and its effect on stability and biological activity. MAbs 2023; 15:2259289. [PMID: 37742207 PMCID: PMC10519368 DOI: 10.1080/19420862.2023.2259289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 09/12/2023] [Indexed: 09/26/2023] Open
Abstract
Despite tyrosine sulfation being a relatively common post-translational modification (PTM) on the secreted proteins of higher eukaryotic organisms, there have been surprisingly few reports of this modification occurring in recombinant monoclonal antibodies (mAbs) expressed by mammalian cell lines and even less information regarding its potential impact on mAb efficacy and stability. This discrepancy is likely due to the extreme lability of this modification using many of the mass spectrometry methods typically used within the biopharmaceutical industry for PTM identification, as well as the possible misidentification as phosphorylation. Here, we identified sulfation on a single tyrosine residue located within the identical variable region sequence of a 2 + 1 bispecific mAbs heavy and heavy-heavy chains using a multi-enzymatic approach in combination with mass spectrometry analysis and examined its impact on binding, efficacy, and physical stability. Unlike previous reports, we found that tyrosine sulfation modestly decreased the mAb cell binding and T cell-mediated killing, primarily by increasing the rate of antigen disassociation as determined from surface plasmon resonance-binding experiments. We also found that, while this acidic modification had no significant impact on the mAb thermal stability, sulfation did modestly increase its rate of aggregation, presumably by lowering the mAb's colloidal stability as indicated by polyethylene glycol induced liquid-liquid phase separation experiments.
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Affiliation(s)
- Christopher B. Lietz
- Department of Pharmaceutical Candidate Optimization - DMPK, Bristol Myers Squibb, San Diego, CA, USA
| | - Ekaterina Deyanova
- Department of Pharmaceutical Candidate Optimization - DPAS, Bristol Myers Squibb, Lawrenceville, NJ, USA
| | - Younhee Cho
- Department of Pharmaceutical Candidate Optimization - DPAS, Bristol Myers Squibb, San Diego, CA, USA
| | - Jon Cordia
- Department of Pharmaceutical Candidate Optimization - DPAS, Bristol Myers Squibb, San Diego, CA, USA
| | - Sarah Franc
- Department of Pharmaceutical Candidate Optimization - DPAS, Bristol Myers Squibb, San Diego, CA, USA
| | - Sally Kabro
- Department of Pharmaceutical Candidate Optimization - DPAS, Bristol Myers Squibb, San Diego, CA, USA
| | - Steven Wang
- Department of Pharmaceutical Candidate Optimization - DPAS, Bristol Myers Squibb, San Diego, CA, USA
| | - David Mikolon
- Department of Biotherapeutics, Bristol Myers Squibb, San Diego, CA, USA
| | - Douglas D. Banks
- Department of Pharmaceutical Candidate Optimization - DPAS, Bristol Myers Squibb, San Diego, CA, USA
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8
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Zhong X, D’Antona AM. A potential antibody repertoire diversification mechanism through tyrosine sulfation for biotherapeutics engineering and production. Front Immunol 2022; 13:1072702. [PMID: 36569848 PMCID: PMC9774471 DOI: 10.3389/fimmu.2022.1072702] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 11/23/2022] [Indexed: 12/13/2022] Open
Abstract
The diversity of three hypervariable loops in antibody heavy chain and light chain, termed the complementarity-determining regions (CDRs), defines antibody's binding affinity and specificity owing to the direct contact between the CDRs and antigens. These CDR regions typically contain tyrosine (Tyr) residues that are known to engage in both nonpolar and pi stacking interaction with antigens through their complementary aromatic ring side chains. Nearly two decades ago, sulfotyrosine residue (sTyr), a negatively charged Tyr formed by Golgi-localized membrane-bound tyrosylprotein sulfotransferases during protein trafficking, were also found in the CDR regions and shown to play an important role in modulating antibody-antigen interaction. This breakthrough finding demonstrated that antibody repertoire could be further diversified through post-translational modifications, in addition to the conventional genetic recombination. This review article summarizes the current advances in the understanding of the Tyr-sulfation modification mechanism and its application in potentiating protein-protein interaction for antibody engineering and production. Challenges and opportunities are also discussed.
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Stewart V, Ronald PC. Sulfotyrosine residues: interaction specificity determinants for extracellular protein-protein interactions. J Biol Chem 2022; 298:102232. [PMID: 35798140 PMCID: PMC9372746 DOI: 10.1016/j.jbc.2022.102232] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 06/21/2022] [Accepted: 06/22/2022] [Indexed: 11/28/2022] Open
Abstract
Tyrosine sulfation, a post-translational modification, can determine and often enhance protein–protein interaction specificity. Sulfotyrosyl residues (sTyrs) are formed by the enzyme tyrosyl-protein sulfotransferase during protein maturation in the Golgi apparatus and most often occur singly or as a cluster within a six-residue span. With both negative charge and aromatic character, sTyr facilitates numerous atomic contacts as visualized in binding interface structural models, thus there is no discernible binding site consensus. Found exclusively in secreted proteins, in this review, we discuss the four broad sequence contexts in which sTyr has been observed: first, a solitary sTyr has been shown to be critical for diverse high-affinity interactions, such as between peptide hormones and their receptors, in both plants and animals. Second, sTyr clusters within structurally flexible anionic segments are essential for a variety of cellular processes, including coreceptor binding to the HIV-1 envelope spike protein during virus entry, chemokine interactions with receptors, and leukocyte rolling cell adhesion. Third, a subcategory of sTyr clusters is found in conserved acidic sequences termed hirudin-like motifs that enable proteins to interact with thrombin; consequently, many proven and potential therapeutic proteins derived from blood-consuming invertebrates depend on sTyrs for their activity. Finally, several proteins that interact with collagen or similar proteins contain one or more sTyrs within an acidic residue array. Refined methods to direct sTyr incorporation in peptides synthesized both in vitro and in vivo, together with continued advances in mass spectrometry and affinity detection, promise to accelerate discoveries of sTyr occurrence and function.
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Affiliation(s)
- Valley Stewart
- Department of Microbiology & Molecular Genetics, University of California, Davis, USA.
| | - Pamela C Ronald
- Department of Plant Pathology, University of California, Davis, USA; Genome Center, University of California, Davis, USA.
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10
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DeLaney K, Phetsanthad A, Li L. ADVANCES IN HIGH-RESOLUTION MALDI MASS SPECTROMETRY FOR NEUROBIOLOGY. MASS SPECTROMETRY REVIEWS 2022; 41:194-214. [PMID: 33165982 PMCID: PMC8106695 DOI: 10.1002/mas.21661] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 09/13/2020] [Indexed: 05/08/2023]
Abstract
Research in the field of neurobiology and neurochemistry has seen a rapid expansion in the last several years due to advances in technologies and instrumentation, facilitating the detection of biomolecules critical to the complex signaling of neurons. Part of this growth has been due to the development and implementation of high-resolution Fourier transform (FT) mass spectrometry (MS), as is offered by FT ion cyclotron resonance (FTICR) and Orbitrap mass analyzers, which improves the accuracy of measurements and helps resolve the complex biological mixtures often analyzed in the nervous system. The coupling of matrix-assisted laser desorption/ionization (MALDI) with high-resolution MS has drastically expanded the information that can be obtained with these complex samples. This review discusses notable technical developments in MALDI-FTICR and MALDI-Orbitrap platforms and their applications toward molecules in the nervous system, including sequence elucidation and profiling with de novo sequencing, analysis of post-translational modifications, in situ analysis, key advances in sample preparation and handling, quantitation, and imaging. Notable novel applications are also discussed to highlight key developments critical to advancing our understanding of neurobiology and providing insight into the exciting future of this field. © 2020 John Wiley & Sons Ltd. Mass Spec Rev.
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Affiliation(s)
- Kellen DeLaney
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA
| | - Ashley Phetsanthad
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA
| | - Lingjun Li
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA
- School of Pharmacy, University of Wisconsin-Madison, 777 Highland Avenue, Madison, WI 53705, USA
- To whom correspondence should be addressed. , Phone: (608) 265-8491, Fax: (608) 262-5345., Mailing Address: 5125 Rennebohm Hall, 777 Highland Avenue, Madison, WI 53706
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Abstract
Monoclonal antibodies are susceptible to chemical and enzymatic modifications during manufacturing, storage, and shipping. Deamidation, isomerization, and oxidation can compromise the potency, efficacy, and safety of therapeutic antibodies. Recently, in silico tools have been used to identify liable residues and engineer antibodies with better chemical stability. Computational approaches for predicting deamidation, isomerization, oxidation, glycation, carbonylation, sulfation, and hydroxylation are reviewed here. Although liable motifs have been used to improve the chemical stability of antibodies, the accuracy of in silico predictions can be improved using machine learning and molecular dynamic simulations. In addition, there are opportunities to improve predictions for specific stress conditions, develop in silico prediction of novel modifications in antibodies, and predict the impact of modifications on physical stability and antigen-binding.
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Affiliation(s)
- Shabdita Vatsa
- Development Services, Lonza Biologics, Singapore, Singapore
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12
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Liu R, Zhang Y, Kumar A, Huhn S, Hullinger L, Du Z. Modulating tyrosine sulfation of recombinant antibodies in CHO cell culture by host selection and sodium chlorate supplementation. Biotechnol J 2021; 16:e2100142. [PMID: 34081410 DOI: 10.1002/biot.202100142] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 05/30/2021] [Accepted: 06/01/2021] [Indexed: 11/10/2022]
Abstract
BACKGROUND Tyrosine sulfation is a post-translational modification found on many surface receptors and plays an important role in cell-cell and cell-matrix interactions. However, tyrosine sulfation of therapeutic antibodies has only been reported very recently. Because of potential potency and immunogenicity concerns, tyrosine sulfation needs to be controlled during the manufacturing process. METHODS AND RESULTS In this study, we explored methods to modulate antibody tyrosine sulfation during cell line development and upstream production process. We found that tyrosine sulfation levels were significantly different in various Chinese hamster ovary (CHO) cell lines due to differential expression of genes in the sulfation pathway including tyrosylprotein sulfotransferase 2 (TPST2) and the sulfation substrate transporter SLC35B2. We also screened chemical inhibitors to reduce tyrosine sulfation in CHO culture and found that sodium chlorate could significantly inhibit tyrosine sulfation while having minimal impact on cell growth and antibody production. We further confirmed this finding in a standard fed-batch production assay. Sodium chlorate at 16 mM markedly inhibited tyrosine sulfation by more than 50% and had no significant impact on antibody titer or quality. CONCLUSION These data suggest that we can control tyrosine sulfation by selecting CHO cell lines based on the expression level of TPST2 and SLC35B2 or adding sodium chlorate in upstream production process.
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Affiliation(s)
- Ren Liu
- Process Cell Sciences, Merck & Co., Inc., Kenilworth, New Jersey, USA
| | - Yixiao Zhang
- Process Cell Sciences, Merck & Co., Inc., Kenilworth, New Jersey, USA
| | - Amit Kumar
- Process Cell Sciences, Merck & Co., Inc., Kenilworth, New Jersey, USA
| | - Steven Huhn
- Process Cell Sciences, Merck & Co., Inc., Kenilworth, New Jersey, USA
| | - Laurie Hullinger
- Process Cell Sciences, Merck & Co., Inc., Kenilworth, New Jersey, USA
| | - Zhimei Du
- Process Cell Sciences, Merck & Co., Inc., Kenilworth, New Jersey, USA
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13
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Gstöttner C, Reusch D, Haberger M, Dragan I, Van Veelen P, Kilgour DPA, Tsybin YO, van der Burgt YEM, Wuhrer M, Nicolardi S. Monitoring glycation levels of a bispecific monoclonal antibody at subunit level by ultrahigh-resolution MALDI FT-ICR mass spectrometry. MAbs 2021; 12:1682403. [PMID: 31630606 PMCID: PMC6927770 DOI: 10.1080/19420862.2019.1682403] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Bispecific monoclonal antibodies (BsAbs) are engineered proteins with multiple functionalities and properties. The "bi-specificity" of these complex biopharmaceuticals is a key characteristic for the development of novel and more effective therapeutic strategies. The high structural complexity of BsAbs poses a challenge to the analytical methods needed for their characterization. Modifications of the BsAb structure, resulting from enzymatic and non-enzymatic processes, further complicate the analysis. An important example of the latter type of modification is glycation, which can occur in the manufacturing process, during storage in the formulation or in vivo after application of the drug. Glycation affects the structure, function, and stability of monoclonal antibodies, and consequently, a detailed analysis of glycation levels is required. Mass spectrometry (MS) plays a key role in the structural characterization of monoclonal antibodies and top-down, middle-up and middle-down MS approaches are increasingly used for the analysis of modifications. Here, we apply a novel middle-up strategy, based on IdeS digestion and matrix-assisted laser desorption ionization (MALDI) Fourier transform ion cyclotron resonance (FT-ICR) MS, to analyze all six different BsAb subunits in a single high-resolution mass spectrum, namely two light chains, two half fragment crystallizable regions and two Fd' regions, thus avoiding upfront chromatography. This method was used to monitor glycation changes during a 168 h forced-glycation experiment. In addition, hot spot glycation sites were localized using top-down and middle-down MALDI-in-source decay FT-ICR MS, which provided complementary information compared to standard bottom-up MS.
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Affiliation(s)
- Christoph Gstöttner
- Leiden University Medical Center, Center for Proteomics and Metabolomics, Leiden, The Netherlands
| | - Dietmar Reusch
- Pharma Technical Development Penzberg, Roche Diagnostics GmbH, Penzberg, Germany
| | - Markus Haberger
- Pharma Technical Development Penzberg, Roche Diagnostics GmbH, Penzberg, Germany
| | - Irina Dragan
- Leiden University Medical Center, Center for Proteomics and Metabolomics, Leiden, The Netherlands
| | - Peter Van Veelen
- Leiden University Medical Center, Center for Proteomics and Metabolomics, Leiden, The Netherlands
| | - David P A Kilgour
- Department of Chemistry, Nottingham Trent University, Nottingham, U.K
| | - Yury O Tsybin
- Spectroswiss, EPFL Innovation Park, Lausanne, Switzerland
| | - Yuri E M van der Burgt
- Leiden University Medical Center, Center for Proteomics and Metabolomics, Leiden, The Netherlands
| | - Manfred Wuhrer
- Leiden University Medical Center, Center for Proteomics and Metabolomics, Leiden, The Netherlands
| | - Simone Nicolardi
- Leiden University Medical Center, Center for Proteomics and Metabolomics, Leiden, The Netherlands
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14
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Boddapati S, Gilmore J, Boone K, Bushey J, Ross J, Gfeller B, McFee W, Rao R, Corrigan G, Chen A, Clarke H, Valliere-Douglass J, Bhargava S. Evidence for co-translational misincorporation of non-canonical amino acid hydroxyproline in recombinant antibodies produced in Chinese Hamster Ovary (CHO) cell lines. PLoS One 2020; 15:e0241250. [PMID: 33119652 PMCID: PMC7595273 DOI: 10.1371/journal.pone.0241250] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Accepted: 10/09/2020] [Indexed: 02/03/2023] Open
Abstract
With the advent of highly sensitive technologies such as tandem mass spectrometry and next-generation sequencing, recombinant antibodies are now routinely analyzed for the presence of low-level sequence variants including amino acid misincorporations. During mAb cell culture process development, we found that proline was replaced with the non-canonical amino acid, hydroxyproline, in the protein sequence. We investigated the relationship between proline content in the cell culture media and proline sequence variants and found that the proline concentration was inversely correlated with the amount of sequence variants detected in the protein sequence. Hydroxyproline incorporation has been previously reported in recombinant proteins produced in mammalian expression systems as a post-translational modification. Given the dependency on proline levels, the mechanism was then investigated. To address the possibility of co-translational misincorporation of hydroxyproline, we used tandem mass spectrometry to measure incorporation of stable-isotope labelled hydroxyproline added to the feed of a production bioreactor. We discovered co-translational misincorporation of labelled hydroxyproline in the recombinant antibody. These findings are significant, since they underscore the need to track non-canonical amino acid incorporation as a co-translational event in CHO cells. Understanding the mechanism of hydroxyproline incorporation is crucial in developing an appropriate control strategy during biologics production.
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Affiliation(s)
- Shanta Boddapati
- Process Sciences, Seattle Genetics Inc, Bothell, WA, United States of America
- * E-mail:
| | - Jason Gilmore
- Process Sciences, Seattle Genetics Inc, Bothell, WA, United States of America
| | - Kyle Boone
- Process Sciences, Seattle Genetics Inc, Bothell, WA, United States of America
| | - John Bushey
- Process Sciences, Seattle Genetics Inc, Bothell, WA, United States of America
| | - Jonathan Ross
- Process Sciences, Seattle Genetics Inc, Bothell, WA, United States of America
| | - Brian Gfeller
- Process Sciences, Seattle Genetics Inc, Bothell, WA, United States of America
| | - William McFee
- Process Sciences, Seattle Genetics Inc, Bothell, WA, United States of America
| | - Romesh Rao
- Process Sciences, Seattle Genetics Inc, Bothell, WA, United States of America
| | - Greg Corrigan
- Upstream Manufacturing, Seattle Genetics Inc, Bothell, WA, United States of America
| | - Aaron Chen
- Process Sciences, Seattle Genetics Inc, Bothell, WA, United States of America
| | - Howard Clarke
- Process Sciences, Seattle Genetics Inc, Bothell, WA, United States of America
| | | | - Swapnil Bhargava
- Process Sciences, Seattle Genetics Inc, Bothell, WA, United States of America
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15
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Nicolardi S, Kilgour DPA, van der Burgt YEM, Wuhrer M. Improved N- and C-Terminal Sequencing of Proteins by Combining Positive and Negative Ion MALDI In-Source Decay Mass Spectrometry. Anal Chem 2020; 92:12429-12436. [PMID: 32803948 PMCID: PMC7498143 DOI: 10.1021/acs.analchem.0c02198] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 08/17/2020] [Indexed: 01/10/2023]
Abstract
The development of various ionization and fragmentation techniques has been of key importance for establishing mass spectrometry (MS) as a powerful tool for protein characterization. One example of this is matrix-assisted laser desorption/ionization (MALDI) combined with in-source decay (ISD) fragmentation that allows mapping of N- and C-terminal regions of large proteins without the need for proteolysis. Positive ion mode ISD fragments are commonly assigned in the mass region above m/z 1000, while MALDI matrix ions generally hamper the detection of smaller singly charged fragments. The ultrahigh resolving power provided by Fourier transform ion cyclotron resonance (FT-ICR) MS partially overcomes this limitation, but to further increase the detection of smaller fragments we have revisited the application of negative ion mode MALDI-ISD and found good coverage of the peptide chain termini starting from c'2 and z'2 fragment ions. For the first time, we demonstrate that the combination of negative and positive ion MALDI FT-ICR MS is a useful tool to improve the characterization of mAbs. The different specificities of the two ion modes allowed us to selectively cover the sequence of the light and heavy chains of mAbs at increased sensitivity. A comprehensive evaluation of positive and negative ion mode MALDI-ISD FT-ICR MS in the m/z range 46-13 500 showed an increased sequence coverage for three standard proteins, namely, myoglobin, SiLuLite mAb, and NIST mAb. The data obtained in the two ion modes were, in part, complementary.
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Affiliation(s)
- Simone Nicolardi
- Center for Proteomics & Metabolomics, Leiden University Medical Center, Albinusdreef 2, Leiden 2333 ZA, The Netherlands
| | - David P A Kilgour
- Department of Chemistry, Nottingham Trent University, Nottingham NG11 0JN, U.K
| | - Yuri E M van der Burgt
- Center for Proteomics & Metabolomics, Leiden University Medical Center, Albinusdreef 2, Leiden 2333 ZA, The Netherlands
| | - Manfred Wuhrer
- Center for Proteomics & Metabolomics, Leiden University Medical Center, Albinusdreef 2, Leiden 2333 ZA, The Netherlands
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16
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Srzentić K, Fornelli L, Tsybin YO, Loo JA, Seckler H, Agar JN, Anderson LC, Bai DL, Beck A, Brodbelt JS, van der Burgt YEM, Chamot-Rooke J, Chatterjee S, Chen Y, Clarke DJ, Danis PO, Diedrich JK, D'Ippolito RA, Dupré M, Gasilova N, Ge Y, Goo YA, Goodlett DR, Greer S, Haselmann KF, He L, Hendrickson CL, Hinkle JD, Holt MV, Hughes S, Hunt DF, Kelleher NL, Kozhinov AN, Lin Z, Malosse C, Marshall AG, Menin L, Millikin RJ, Nagornov KO, Nicolardi S, Paša-Tolić L, Pengelley S, Quebbemann NR, Resemann A, Sandoval W, Sarin R, Schmitt ND, Shabanowitz J, Shaw JB, Shortreed MR, Smith LM, Sobott F, Suckau D, Toby T, Weisbrod CR, Wildburger NC, Yates JR, Yoon SH, Young NL, Zhou M. Interlaboratory Study for Characterizing Monoclonal Antibodies by Top-Down and Middle-Down Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:1783-1802. [PMID: 32812765 PMCID: PMC7539639 DOI: 10.1021/jasms.0c00036] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The Consortium for Top-Down Proteomics (www.topdownproteomics.org) launched the present study to assess the current state of top-down mass spectrometry (TD MS) and middle-down mass spectrometry (MD MS) for characterizing monoclonal antibody (mAb) primary structures, including their modifications. To meet the needs of the rapidly growing therapeutic antibody market, it is important to develop analytical strategies to characterize the heterogeneity of a therapeutic product's primary structure accurately and reproducibly. The major objective of the present study is to determine whether current TD/MD MS technologies and protocols can add value to the more commonly employed bottom-up (BU) approaches with regard to confirming protein integrity, sequencing variable domains, avoiding artifacts, and revealing modifications and their locations. We also aim to gather information on the common TD/MD MS methods and practices in the field. A panel of three mAbs was selected and centrally provided to 20 laboratories worldwide for the analysis: Sigma mAb standard (SiLuLite), NIST mAb standard, and the therapeutic mAb Herceptin (trastuzumab). Various MS instrument platforms and ion dissociation techniques were employed. The present study confirms that TD/MD MS tools are available in laboratories worldwide and provide complementary information to the BU approach that can be crucial for comprehensive mAb characterization. The current limitations, as well as possible solutions to overcome them, are also outlined. A primary limitation revealed by the results of the present study is that the expert knowledge in both experiment and data analysis is indispensable to practice TD/MD MS.
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Affiliation(s)
- Kristina Srzentić
- Northwestern University, Evanston, Illinois 60208-0001, United States
| | - Luca Fornelli
- Northwestern University, Evanston, Illinois 60208-0001, United States
| | - Yury O Tsybin
- Spectroswiss, EPFL Innovation Park, Building I, 1015 Lausanne, Switzerland
| | - Joseph A Loo
- University of California-Los Angeles, Los Angeles, California 90095, United States
| | - Henrique Seckler
- Northwestern University, Evanston, Illinois 60208-0001, United States
| | - Jeffrey N Agar
- Northeastern University, Boston, Massachusetts 02115, United States
| | - Lissa C Anderson
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, United States
| | - Dina L Bai
- University of Virginia, Charlottesville, Virginia 22901, United States
| | - Alain Beck
- Centre d'immunologie Pierre Fabre, 74160 Saint-Julien-en-Genevois, France
| | | | | | | | | | - Yunqiu Chen
- Biogen, Inc., Cambridge, Massachusetts 02142-1031, United States
| | - David J Clarke
- The University of Edinburgh, EH9 3FJ Edinburgh, United Kingdom
| | - Paul O Danis
- Consortium for Top-Down Proteomics, Cambridge, Massachusetts 02142, United States
| | - Jolene K Diedrich
- The Scripps Research Institute, La Jolla, California 92037, United States
| | | | | | - Natalia Gasilova
- Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Ying Ge
- University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Young Ah Goo
- University of Maryland, Baltimore, Maryland 21201, United States
| | - David R Goodlett
- University of Maryland, Baltimore, Maryland 21201, United States
| | - Sylvester Greer
- University of Texas at Austin, Austin, Texas 78712-1224, United States
| | | | - Lidong He
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, United States
| | | | - Joshua D Hinkle
- University of Virginia, Charlottesville, Virginia 22901, United States
| | - Matthew V Holt
- Baylor College of Medicine, Houston, Texas 77030-3411, United States
| | - Sam Hughes
- The University of Edinburgh, EH9 3FJ Edinburgh, United Kingdom
| | - Donald F Hunt
- University of Virginia, Charlottesville, Virginia 22901, United States
| | - Neil L Kelleher
- Northwestern University, Evanston, Illinois 60208-0001, United States
| | - Anton N Kozhinov
- Spectroswiss, EPFL Innovation Park, Building I, 1015 Lausanne, Switzerland
| | - Ziqing Lin
- University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | | | - Alan G Marshall
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, United States
- Florida State University, Tallahassee, Florida 32310-4005, United States
| | - Laure Menin
- Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Robert J Millikin
- University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | | | - Simone Nicolardi
- Leiden University Medical Centre, 2300 RC Leiden, The Netherlands
| | - Ljiljana Paša-Tolić
- Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | | | - Neil R Quebbemann
- University of California-Los Angeles, Los Angeles, California 90095, United States
| | | | - Wendy Sandoval
- Genentech, Inc., South San Francisco, California 94080-4990, United States
| | - Richa Sarin
- Biogen, Inc., Cambridge, Massachusetts 02142-1031, United States
| | | | | | - Jared B Shaw
- Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | | | - Lloyd M Smith
- University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Frank Sobott
- University of Antwerp, 2000 Antwerp, Belgium
- University of Leeds, LS2 9JT Leeds, United Kingdom
| | | | - Timothy Toby
- Northwestern University, Evanston, Illinois 60208-0001, United States
| | - Chad R Weisbrod
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, United States
| | - Norelle C Wildburger
- Washington University School of Medicine, St. Louis, Missouri 63110, United States
| | - John R Yates
- The Scripps Research Institute, La Jolla, California 92037, United States
| | - Sung Hwan Yoon
- University of Maryland, Baltimore, Maryland 21201, United States
| | - Nicolas L Young
- Baylor College of Medicine, Houston, Texas 77030-3411, United States
| | - Mowei Zhou
- Pacific Northwest National Laboratory, Richland, Washington 99354, United States
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17
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Nicolardi S, Kilgour DPA, Dolezal N, Drijfhout JW, Wuhrer M, van der Burgt YEM. Evaluation of Sibling and Twin Fragment Ions Improves the Structural Characterization of Proteins by Top-Down MALDI In-Source Decay Mass Spectrometry. Anal Chem 2020; 92:5871-5881. [PMID: 32212639 PMCID: PMC7178258 DOI: 10.1021/acs.analchem.9b05683] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
![]()
Comprehensive determination
of primary sequence and identification
of post-translational modifications (PTMs) are key elements in protein
structural analysis. Various mass spectrometry (MS) based fragmentation
techniques are powerful approaches for mapping both the amino acid
sequence and PTMs; one of these techniques is matrix-assisted laser
desorption/ionization (MALDI), combined with in-source decay (ISD)
fragmentation and Fourier-transform ion cyclotron resonance (FT-ICR)
MS. MALDI-ISD MS protein analysis involves only minimal sample preparation
and does not require spectral deconvolution. The resulting MALDI-ISD
MS data is complementary to electrospray ionization-based MS/MS sequencing
readouts, providing knowledge on the types of fragment ions is available.
In this study, we evaluate the isotopic distributions of z′ ions in protein top-down MALDI-ISD FT-ICR mass spectra and
show why these distributions can deviate from theoretical profiles
as a result of co-occurring and isomeric z and y-NH3 ions. Two synthetic peptides, containing
either normal or deuterated alanine residues, were used to confirm
the presence and unravel the identity of isomeric z and y-NH3 fragment ions (“twins”).
Furthermore, two reducing MALDI matrices, namely 1,5-diaminonaphthalene
and N-phenyl-p-phenylenediamine
were applied that yield ISD mass spectra with different fragment ion
distributions. This study demonstrates that the relative abundance
of isomeric z and y-NH3 ions requires consideration for accurate and confident assignments
of z′ ions in MALDI-ISD FT-ICR mass spectra.
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Affiliation(s)
- Simone Nicolardi
- Center for Proteomics & Metabolomics, Leiden University Medical Center, Leiden 2333, ZA, The Netherlands
| | - David P A Kilgour
- Department of Chemistry, Nottingham Trent University, Nottingham NG11 0JN, United Kingdom
| | - Natasja Dolezal
- Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden 2333, ZA, The Netherlands
| | - Jan W Drijfhout
- Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden 2333, ZA, The Netherlands
| | - Manfred Wuhrer
- Center for Proteomics & Metabolomics, Leiden University Medical Center, Leiden 2333, ZA, The Netherlands
| | - Yuri E M van der Burgt
- Center for Proteomics & Metabolomics, Leiden University Medical Center, Leiden 2333, ZA, The Netherlands
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