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Koy C, Röwer C, Thiesen HJ, Neamtu A, Glocker MO. Intact Transition Epitope Mapping-Force Interferences by Variable Extensions (ITEM-FIVE). Biomolecules 2024; 14:454. [PMID: 38672470 PMCID: PMC11048379 DOI: 10.3390/biom14040454] [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: 02/28/2024] [Revised: 03/27/2024] [Accepted: 03/28/2024] [Indexed: 04/28/2024] Open
Abstract
Investigations on binding strength differences of non-covalent protein complex components were performed by mass spectrometry. T4 fibritin foldon (T4Ff) is a well-studied miniprotein, which together with its biotinylated version served as model system to represent a compactly folded protein to which an Intrinsically Disordered Region (IDR) was attached. The apparent enthalpies of the gas phase dissociation reactions of the homo-trimeric foldon F-F-F and of the homo-trimeric triply biotinylated foldon bF-bF-bF have been determined to be rather similar (3.32 kJ/mol and 3.85 kJ/mol) but quite distinct from those of the singly and doubly biotinylated hetero-trimers F-F-bF and F-bF-bF (1.86 kJ/mol and 1.08 kJ/mol). Molecular dynamics simulations suggest that the ground states of the (biotinylated) T4Ff trimers are highly symmetric and well comparable to each other, indicating that the energy levels of all four (biotinylated) T4Ff trimer ground states are nearly indistinguishable. The experimentally determined differences and/or similarities in enthalpies of the complex dissociation reactions are explained by entropic spring effects, which are noticeable in the T4Ff hetero-trimers but not in the T4Ff homo-trimers. A lowering of the transition state energy levels of the T4Ff hetero-trimers seems likely because the biotin moieties, mimicking intrinsically disordered regions (IDRs), induced asymmetries in the transition states of the biotinylated T4Ff hetero-trimers. This transition state energy level lowering effect is absent in the T4Ff homo-trimer, as well as in the triply biotinylated T4Ff homo-trimer. In the latter, the IDR-associated entropic spring effects on complex stability cancel each other out. ITEM-FIVE enabled semi-quantitative determination of energy differences of complex dissociation reactions, whose differences were modulated by IDRs attached to compactly folded proteins.
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Affiliation(s)
- Cornelia Koy
- Proteome Center Rostock, Medical Faculty and Natural Science Faculty, University of Rostock Schillingallee 69, 18057 Rostock, Germany; (C.K.)
| | - Claudia Röwer
- Proteome Center Rostock, Medical Faculty and Natural Science Faculty, University of Rostock Schillingallee 69, 18057 Rostock, Germany; (C.K.)
| | - Hans-Jürgen Thiesen
- Institute for Immunology, Medical Faculty, University of Rostock, Schillingallee 70, 18057 Rostock, Germany;
| | - Andrei Neamtu
- Department of Physiology, “Gr. T. Popa” University of Medicine and Pharmacy, Str. Universitatii nr. 16, 700115 Iasi, Romania
- TRANSCEND Centre, Regional Institute of Oncology (IRO) Iasi, Str. General Henri Mathias Berthelot, Nr. 2–4, 700483 Iasi, Romania
| | - Michael O. Glocker
- Proteome Center Rostock, Medical Faculty and Natural Science Faculty, University of Rostock Schillingallee 69, 18057 Rostock, Germany; (C.K.)
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Röwer C, Olaleye OO, Bischoff R, Glocker MO. Mass Spectrometric ITEM-ONE and ITEM-TWO Analyses Confirm and Refine an Assembled Epitope of an Anti-Pertuzumab Affimer. Biomolecules 2023; 14:24. [PMID: 38254624 PMCID: PMC10813730 DOI: 10.3390/biom14010024] [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: 10/18/2023] [Revised: 12/13/2023] [Accepted: 12/21/2023] [Indexed: 01/24/2024] Open
Abstract
Intact Transition Epitope Mapping-One-step Non-covalent force Exploitation (ITEM-ONE) analysis reveals an assembled epitope on the surface of Pertuzumab, which is recognized by the anti-Pertuzumab affimer 00557_709097. It encompasses amino acid residues NSGGSIYNQRFKGR, which are part of CDR2, as well as residues FTLSVDR, which are located on the variable region of Pertuzumab's heavy chain and together form a surface area of 1381.46 Å2. Despite not being part of Pertuzumab's CDR2, the partial sequence FTLSVDR marks a unique proteotypic Pertuzumab peptide. Binding between intact Pertuzumab and the anti-Pertuzumab affimer was further investigated using the Intact Transition Epitope Mapping-Thermodynamic Weak-force Order (ITEM-TWO) approach. Quantitative analysis of the complex dissociation reaction in the gas phase afforded a quasi-equilibrium constant (KD m0g#) of 3.07 × 10-12. The experimentally determined apparent enthalpy (ΔHm0g#) and apparent free energy (ΔGm0g#) of the complex dissociation reaction indicate that the opposite reaction-complex formation-is spontaneous at room temperature. Due to strong binding to Pertuzumab and because of recognizing Pertuzumab's unique partial amino acid sequences, the anti-Pertuzumab affimer 00557_709097 is considered excellently suitable for implementation in Pertuzumab quantitation assays as well as for the accurate therapeutic drug monitoring of Pertuzumab in biological fluids.
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Affiliation(s)
- Claudia Röwer
- Proteome Center Rostock, Medical Faculty and Natural Science Faculty, University of Rostock, 18057 Rostock, Germany
| | - Oladapo O. Olaleye
- Department of Analytical Biochemistry, Faculty of Science & Engineering, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Rainer Bischoff
- Department of Analytical Biochemistry, Faculty of Science & Engineering, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Michael O. Glocker
- Proteome Center Rostock, Medical Faculty and Natural Science Faculty, University of Rostock, 18057 Rostock, Germany
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Koy C, Glocker UM, Danquah BD, Glocker MO. Native and compactly folded in-solution conformers of pepsin are revealed and distinguished by mass spectrometric ITEM-TWO analyses of gas-phase pepstatin A - pepsin complex binding strength differences. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2023; 29:303-312. [PMID: 37259551 DOI: 10.1177/14690667231178999] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Pepsin, because of its optimal activity at low acidic pH, has gained importance in mass spectrometric proteome research as a readily available and easy-to-handle protease. Pepsin has also been study object of protein higher-order structure analyses, but questions about how to best investigate pepsin in-solution conformers still remain. We first determined dependencies of pepsin ion charge structures on solvent pH which indicated the in-solution existence of (a) natively folded pepsin (N) which by nanoESI-MS analysis gave rise to a narrow charge state distribution with an 11-fold protonated most intense ion signal, (b) unfolded pepsin (U) with a rather broad ion charge state distribution whose highest ion signal carried 25 protons, and (c) a compactly folded pepsin conformer (C) with a narrow charge structure and a 12-fold protonated ion signal in the center of its charge state envelope. Because pepsin is a protease, unfolded pepsin became its own substrate in solution at pH 6.6 since at this pH some portion of pepsin maintained a compact/native fold which displayed enzymatic activity. Subsequent mass spectrometric ITEM-TWO analyses of pepstatin A - pepsin complex dissociation reactions in the gas phase confirmed a very strong binding of pepstatin A by natively folded pepsin (N). ITEM-TWO further revealed the existence of two compactly folded in-solution pepsin conformers (Ca and Cb) which also were able to bind pepstatin A. Binding strengths of the respective compactly folded pepsin conformer-containing complexes could be determined and apparent gas phase complex dissociation constants and reaction enthalpies differentiated these from each other and from the pepstatin A - pepsin complex which had been formed from natively folded pepsin. Thus, ITEM-TWO turned out to be well suited to pinpoint in-solution pepsin conformers by interrogating quantitative traits of pepstatin A - pepsin complexes in the gas phase.
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Affiliation(s)
- Cornelia Koy
- Proteome Center Rostock, Medical Faculty and Natural Science Faculty, University of Rostock, Rostock, Germany
| | - Ursula M Glocker
- Proteome Center Rostock, Medical Faculty and Natural Science Faculty, University of Rostock, Rostock, Germany
| | - Bright D Danquah
- Proteome Center Rostock, Medical Faculty and Natural Science Faculty, University of Rostock, Rostock, Germany
| | - Michael O Glocker
- Proteome Center Rostock, Medical Faculty and Natural Science Faculty, University of Rostock, Rostock, Germany
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Scherf M, Koy C, Röwer C, Neamtu A, Glocker MO. Characterization of Phosphorylation-Dependent Antibody Binding to Cancer-Mutated Linkers of C 2H 2 Zinc Finger Proteins by Intact Transition Epitope Mapping-Thermodynamic Weak-Force Order Analysis. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2023; 34:171-181. [PMID: 36656134 DOI: 10.1021/jasms.2c00244] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
With Intact Transition Epitope Mapping-Thermodynamic Weak-force Order (ITEM-TWO) analysis in combination with molecular modeling, the phosphorylation-dependent molecular recognition motif of the anti-HpTGEKP antibody has been investigated with binary and ternary component mixtures consisting of antibody and (phospho-) peptides. Amino acid sequences have been selected to match either the antibody's recognition motif or the cancer-related zinc finger protein mutations and phosphorylations of the respective amino acid residues. Upon electrospraying of all the components of the mixtures, that is, hexapeptides, antibody, and intact immune complexes, the produced ions were subjected to mass spectrometric mass filtering. The antibody ions as well as the immune complex ions traversed into the mass spectrometer's collision chamber, whereas paths of unbound peptide ions were blocked prior to entering the collision cell. After dissociation of the multiply charged immune complexes in the gas phase, the complex-released peptide ions were recorded after having traversed the second mass filter. Complex-released peptides were unambiguously identified by their masses using mass analysis with isotope resolution. From the results of our studies with seven (phospho-) peptides with distinct amino acid sequences, which resembled either the antibody's binding motif or mutations, we conclude the following: (i) A negatively charged phospho group, located near the peptide's N-terminus is mandatory for antibody binding when placed on the peptide surface at a precise distance to the C-terminally located positively charged ε-amino group of a lysinyl residue. (ii) A bulky amino acid residue, such as the tyrosinyl residue at the N-terminal position of the (phospho-) threoninyl residue, abolishes antibody binding. (iii) Two closely spaced phospho groups negatively interfere with the surface polarity pattern and abolish antibody binding as well. (iv) Non-phosphorylated peptides are not binding partners of the anti-HpTGEKP antibody.
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Affiliation(s)
- Maximilian Scherf
- Proteome Center Rostock, University Medicine Rostock and University of Rostock, Schillingallee 69, 18059 Rostock, Germany
| | - Cornelia Koy
- Proteome Center Rostock, University Medicine Rostock and University of Rostock, Schillingallee 69, 18059 Rostock, Germany
| | - Claudia Röwer
- Proteome Center Rostock, University Medicine Rostock and University of Rostock, Schillingallee 69, 18059 Rostock, Germany
| | - Andrei Neamtu
- TRANSCEND Centre, Regional Institute of Oncology (IRO) Iasi, Str. General Henri Mathias Berthelot Nr. 2-4, 700483 Iasi, Romania
- Department of Physiology, Grigore T. Popa University of Medicine and Pharmacy of Iasi, Str. Universitatii Nr. 16, 700115 Iasi, Romania
| | - Michael O Glocker
- Proteome Center Rostock, University Medicine Rostock and University of Rostock, Schillingallee 69, 18059 Rostock, Germany
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Intact Transition Epitope Mapping-Force Differences between Original and Unusual Residues (ITEM-FOUR). Biomolecules 2023; 13:biom13010187. [PMID: 36671572 PMCID: PMC9856199 DOI: 10.3390/biom13010187] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 01/06/2023] [Accepted: 01/13/2023] [Indexed: 01/19/2023] Open
Abstract
Antibody-based point-of-care diagnostics have become indispensable for modern medicine. In-depth analysis of antibody recognition mechanisms is the key to tailoring the accuracy and precision of test results, which themselves are crucial for targeted and personalized therapy. A rapid and robust method is desired by which binding strengths between antigens and antibodies of concern can be fine-mapped with amino acid residue resolution to examine the assumedly serious effects of single amino acid polymorphisms on insufficiencies of antibody-based detection capabilities of, e.g., life-threatening conditions such as myocardial infarction. The experimental ITEM-FOUR approach makes use of modern mass spectrometry instrumentation to investigate intact immune complexes in the gas phase. ITEM-FOUR together with molecular dynamics simulations, enables the determination of the influences of individually exchanged amino acid residues within a defined epitope on an immune complex's binding strength. Wild-type and mutated epitope peptides were ranked according to their experimentally determined dissociation enthalpies relative to each other, thereby revealing which single amino acid polymorphism caused weakened, impaired, and even abolished antibody binding. Investigating a diagnostically relevant human cardiac Troponin I epitope for which seven nonsynonymous single nucleotide polymorphisms are known to exist in the human population tackles a medically relevant but hitherto unsolved problem of current antibody-based point-of-care diagnostics.
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Scherf M, Danquah BD, Koy C, Lorenz P, Steinbeck F, Neamtu A, Thiesen H, Glocker MO. Epitope Fine Mapping by Mass Spectrometry: Investigations of Immune Complexes Consisting of Monoclonal Anti-HpTGEKP Antibody and Zinc Finger Protein Linker Phospho-Hexapeptides. Chembiochem 2022; 23:e202200390. [PMID: 35950614 PMCID: PMC9826235 DOI: 10.1002/cbic.202200390] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 08/03/2022] [Indexed: 01/11/2023]
Abstract
Accurate formation of antibody-antigen complexes has been relied on in both, multitudes of scientific projects and ample therapeutic and diagnostic applications. Mass spectrometrically determined dissociation behavior of immune complexes with the anti-HpTGEKP antibody revealed that the ten most frequently occurring phospho-hexapeptide linker sequences from C2H2 zinc finger proteins could be divided into two classes: orthodox binders, where strong noncovalent interactions developed as anticipated, and unorthodox binders with deviating structures and weaker binding. Phosphorylation of threonine was compulsory for antibody binding in an orthodox manner. Gas phase dissociation energy determinations of seven C2H2 zinc finger protein linker phospho-hexapeptides with orthodox binding properties revealed a bipolar binding motif of the antibody paratope. Epitope peptides, which in addition to the negatively charged phospho-threonine residue were C-terminally flanked by positively charged residues provided stronger binding, i. e. dissociation was endothermic, than peptides with acidic amino acid residues at these positions, for which dissociation was exothermic.
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Affiliation(s)
- Maximilian Scherf
- Proteome Center RostockUniversity Medicine Rostock and University of RostockSchillingallee 6918059RostockGermany
| | - Bright D. Danquah
- Proteome Center RostockUniversity Medicine Rostock and University of RostockSchillingallee 6918059RostockGermany
| | - Cornelia Koy
- Proteome Center RostockUniversity Medicine Rostock and University of RostockSchillingallee 6918059RostockGermany
| | - Peter Lorenz
- Institute of ImmunologyUniversity Medicine RostockSchillingallee 7018059RostockGermany
| | - Felix Steinbeck
- Institute of ImmunologyUniversity Medicine RostockSchillingallee 7018059RostockGermany,Gesellschaft für Individualisierte Medizin mbH (IndyMed)Industriestrasse 1518069RostockGermany
| | - Andrei Neamtu
- Department of PhysiologyGr. T. Popa University of Medicine and Pharmacy of IasiStr. Universitatii nr. 16Iasi Jud.Romania
| | - Hans‐Jürgen Thiesen
- Institute of ImmunologyUniversity Medicine RostockSchillingallee 7018059RostockGermany,Gesellschaft für Individualisierte Medizin mbH (IndyMed)Industriestrasse 1518069RostockGermany
| | - Michael O. Glocker
- Proteome Center RostockUniversity Medicine Rostock and University of RostockSchillingallee 6918059RostockGermany
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