1
|
Kirsch ZJ, Vachet RW. Proteins Can Withstand More Extensive Labeling while Providing Accurate Structural Information in Covalent Labeling-Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2024; 35:1030-1039. [PMID: 38581471 PMCID: PMC11167616 DOI: 10.1021/jasms.4c00043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/08/2024]
Abstract
Diethylpyrocarbonate (DEPC) covalent labeling-mass spectrometry (CL-MS) has been extensively utilized to study protein structure and interactions owing to its ease of use, commercial availability, and broad labeling of nucleophilic residues. During typical CL-MS experiments with DEPC, the extent of labeling is kept low to avoid any structural perturbations resulting from covalent modification of the protein. In this study, we demonstrate that proteins can be labeled more extensively via DEPC and still provide accurate structural information. To show this, we modeled labeling kinetics over a range of DEPC concentrations and used molecular dynamics simulations to investigate the molecular-level effects of extensive labeling on the protein structure. Our results indicate that higher extents of DEPC labeling do not significantly perturb the protein structure and can lead to improved precision, detectability of labeled peptides, and protein structural resolution. Furthermore, higher extents of labeling enable better identification of protein-ligand binding sites where lower extents of modification provide ambiguous results.
Collapse
Affiliation(s)
- Zachary J. Kirsch
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| | - Richard W. Vachet
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts 01003, United States
| |
Collapse
|
2
|
Dhingra K, Sinha I, Snyder M, Roush D, Cramer SM. Exploring preferred binding domains of IgG1 mAbs to multimodal adsorbents using a combined biophysics and simulation approach. Biotechnol Prog 2024; 40:e3415. [PMID: 38043031 DOI: 10.1002/btpr.3415] [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: 08/28/2023] [Revised: 10/19/2023] [Accepted: 11/13/2023] [Indexed: 12/04/2023]
Abstract
In this work, we employ a recently developed biophysical technique that uses diethylpyrocarbonate (DEPC) covalent labeling and mass spectrometry for the identification of mAb binding patches to two multimodal cation exchange resins at different pH. This approach compares the labeling results obtained in the bound and unbound states to identify residues that are sterically shielded and thus located in the mAb binding domains. The results at pH 6 for one mAb (mAb B) indicated that while the complementarity determining region (CDR) had minimal interactions with both resins, the FC domain was actively involved in binding. In contrast, DEPC/MS data with another mAb (mAb C) indicated that both the CDR and FC domains were actively involved in binding. These results corroborated chromatographic retention data with these two mAbs and their fragments and helped to explain the significantly stronger retention of both the intact mAb C and its Fab fragment. In contrast, labeling results with mAb C at pH 7, indicated that only the CDR played a significant role in resin binding, again corroborating chromatographic data. The binding domains identified from the DEPC/MS experiments were also examined using protein surface hydrophobicity maps obtained using a recently developed sparse sampling molecular dynamics (MD) approach in concert with electrostatic potential maps. These results demonstrate that the DEPC covalent labeling/mass spectrometry technique can provide important information about the domain contributions of multidomain proteins such as monoclonal antibodies when interacting with multimodal resins over a range of pH conditions.
Collapse
Affiliation(s)
- Kabir Dhingra
- Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York, USA
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York, USA
| | - Imee Sinha
- Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York, USA
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York, USA
| | - Mark Snyder
- Process Chemistry Division, Bio-Rad Laboratories, Hercules, California, USA
| | - David Roush
- Process R&D, Merck &Co., Inc., Rahway, New Jersey, USA
| | - Steven M Cramer
- Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York, USA
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York, USA
| |
Collapse
|
3
|
Kuehl NJ, Taylor MT. Rapid Biomolecular Trifluoromethylation Using Cationic Aromatic Sulfonate Esters as Visible-Light-Triggered Radical Photocages. J Am Chem Soc 2023; 145:22878-22884. [PMID: 37819426 PMCID: PMC11076010 DOI: 10.1021/jacs.3c08098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
Described here is a photodecaging approach to radical trifluoromethylation of biomolecules. This was accomplished by designing a quinolinium sulfonate ester that, upon absorption of visible light, achieves decaging via photolysis of the sulfonate ester to ultimately liberate free trifluoromethyl radicals that are trapped by π-nucleophiles in biomolecules. This photodecaging process enables protein and protein-interaction mapping experiments using trifluoromethyl radicals that require only 1 s reaction times and low photocage concentrations. In these experiments, aromatic side chains are labeled in an environmentally dependent fashion, with selectivity observed for tryptophan (Trp), followed by histidine (His) and tyrosine (Tyr). Scalable peptide trifluoromethylation through photodecaging is also demonstrated, where bespoke peptides harboring trifluoromethyl groups at tryptophan residues can be synthesized with 5-7 min reaction times and good yields.
Collapse
Affiliation(s)
- Nicholas J. Kuehl
- Department of Chemistry, University of Wyoming, Laramie, WY 82071, United States
| | - Michael T. Taylor
- Department of Chemistry & Biochemistry, University of Arizona, Tucson, AZ 85721, United States
| |
Collapse
|
4
|
Dhingra K, Gudhka RB, Cramer SM. Evaluation of preferred binding regions on ubiquitin and IgG1 F C for interacting with multimodal cation exchange resins using DEPC labeling/mass spectrometry. Biotechnol Bioeng 2023; 120:1592-1604. [PMID: 36814367 DOI: 10.1002/bit.28361] [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: 12/05/2022] [Revised: 02/06/2023] [Accepted: 02/14/2023] [Indexed: 02/24/2023]
Abstract
There is significant interest in identifying the preferred binding domains of biological products to various chromatographic materials. In this work, we develop a biophysical technique that uses diethyl pyrocarbonate (DEPC) based covalent labeling in concert with enzymatic digestion and mass spectrometry to identify the binding patches for proteins bound to commercially available multimodal (MM) cation exchange chromatography resins. The technique compares the changes in covalent labeling of the protein in solution and in the bound state and uses the differences in this labeling to identify residues that are sterically shielded upon resin binding and, therefore, potentially involved in the resin binding process. Importantly, this approach enables the labeling of many amino acids and can be carried out over a pH range of 5.5-7.5, thus enabling the protein surface mapping at conditions of interest in MM cation exchange systems. The protocol is first developed using the model protein ubiquitin and the results indicate that lysine residues located on the front face of the protein show dramatic changes in DEPC labeling while residues present on other regions have minimal or no reductions. This indicates that the front face of ubiquitin is likely involved in resin binding. In addition, surface property maps indicate that the hypothesized front face binding region consists of overlapping positively charged and hydrophobic patches. The technique is then employed with an IgG1 FC and the results indicate that residues on the CH 2-CH 3 interface and the hinge are significantly sterically shielded upon binding to the resin. Further, these regions are again associated with significant overlap of positively charged and hydrophobic patches. On the other hand, while, residues on the CH 2 and the front face of the IgG1 FC also exhibited some changes in DEPC labeling upon binding, these regions have less distinct charged and hydrophobic patches. Importantly, the hypothesized binding patches identified for both ubiquitin and FC using this approach are shown to be consistent with previously reported NMR studies. In contrast to NMR, this new approach enables the identification of preferred binding regions without the need for isotopically labeled proteins or chemical shift assignments. The technique developed in this work sets the stage for the evaluation of the binding domains of a wide range of biological products to chromatographic surfaces, with important implications for designing biomolecules with improved biomanufacturability properties.
Collapse
Affiliation(s)
- Kabir Dhingra
- Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York, USA.,Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York, USA
| | - Ronak B Gudhka
- Process Development, Drug Substance Biologics, Amgen, Cambridge, Massachusetts, USA
| | - Steven M Cramer
- Howard P. Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York, USA.,Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York, USA
| |
Collapse
|
5
|
Advances in Mass Spectrometry-based Epitope Mapping of Protein Therapeutics. J Pharm Biomed Anal 2022; 215:114754. [DOI: 10.1016/j.jpba.2022.114754] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 03/16/2022] [Accepted: 04/03/2022] [Indexed: 11/21/2022]
|
6
|
Biehn SE, Picarello DM, Pan X, Vachet RW, Lindert S. Accounting for Neighboring Residue Hydrophobicity in Diethylpyrocarbonate Labeling Mass Spectrometry Improves Rosetta Protein Structure Prediction. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:584-591. [PMID: 35147431 PMCID: PMC8988852 DOI: 10.1021/jasms.1c00373] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Covalent labeling mass spectrometry allows for protein structure elucidation via covalent modification and identification of exposed residues. Diethylpyrocarbonate (DEPC) is a commonly used covalent labeling reagent that provides insight into structure through the labeling of lysine, histidine, serine, threonine, and tyrosine residues. We recently implemented a Rosetta algorithm that used binary DEPC labeling data to improve protein structure prediction efforts. In this work, we improved on our modeling efforts by accounting for the level of hydrophobicity of neighboring residues in the microenvironment of serine, threonine, and tyrosine residues to obtain a more accurate estimate of the hydrophobic neighbor count. This was incorporated into Rosetta functionality, along with considerations for solvent-exposed histidine and lysine residues. Overall, our new Rosetta score term successfully identified best scoring models with less than 2 Å root-mean-squared deviations (RMSDs) for five of the seven benchmark proteins tested. We additionally developed a confidence metric to measure prediction success for situations in which a native structure is unavailable.
Collapse
Affiliation(s)
- Sarah E. Biehn
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH, 43210, United States
| | - Danielle M. Picarello
- Department of Bioengineering, Lehigh University, Bethlehem, PA 18015, United States and Rosetta Commons Research Experience for Undergraduates, Rosetta Commons
| | - Xiao Pan
- Department of Chemistry, University of Massachusetts, Amherst, Amherst, MA 01003, United States
| | - Richard W. Vachet
- Department of Chemistry, University of Massachusetts, Amherst, Amherst, MA 01003, United States
| | - Steffen Lindert
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH, 43210, United States
| |
Collapse
|
7
|
Pan X, Kirsch ZJ, Vachet RW. Distinguishing Histidine Tautomers in Proteins Using Covalent Labeling-Mass Spectrometry. Anal Chem 2022; 94:1003-1010. [PMID: 34962759 PMCID: PMC8787799 DOI: 10.1021/acs.analchem.1c03902] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
In this work, we use diethylpyrocarbonate (DEPC)-based covalent labeling together with LC-MS/MS analysis to distinguish the two sidechain tautomers of histidine residues in peptides and proteins. From labeling experiments on model peptides, we demonstrate that DEPC reacts equally with both tautomeric forms to produce chemically different products with distinct dissociation patterns and LC retention times, allowing the ratios of the two tautomers to be determined in peptides and proteins. Upon measuring the tautomer ratios of several histidine residues in myoglobin, we find good agreement with previous 2D NMR data on this protein. Because our DEPC labeling/MS approach is simpler, faster, and more precise than 2D NMR, our method will be a valuable way to determine how protein structure enforces histidine sidechain tautomerization. Because the tautomeric state of histidine residues is often important for protein structure and function, the ability of DEPC labeling/MS to distinguish histidine tautomers should equip researchers with a tool to understand the histidine residue structure and function more deeply in proteins.
Collapse
|
8
|
Biehn SE, Limpikirati P, Vachet RW, Lindert S. Utilization of Hydrophobic Microenvironment Sensitivity in Diethylpyrocarbonate Labeling for Protein Structure Prediction. Anal Chem 2021; 93:8188-8195. [PMID: 34061512 DOI: 10.1021/acs.analchem.1c00395] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Diethylpyrocarbonate (DEPC) labeling analyzed with mass spectrometry can provide important insights into higher order protein structures. It has been previously shown that neighboring hydrophobic residues promote a local increase in DEPC concentration such that serine, threonine, and tyrosine residues are more likely to be labeled despite low solvent exposure. In this work, we developed a Rosetta algorithm that used the knowledge of labeled and unlabeled serine, threonine, and tyrosine residues and assessed their local hydrophobic environment to improve protein structure prediction. Additionally, DEPC-labeled histidine and lysine residues with higher relative solvent accessible surface area values (i.e., more exposed) were scored favorably. Application of our score term led to reductions of the root-mean-square deviations (RMSDs) of the lowest scoring models. Additionally, models that scored well tended to have lower RMSDs. A detailed tutorial describing our protocol and required command lines is included. Our work demonstrated the considerable potential of DEPC covalent labeling data to be used for accurate higher order structure determination.
Collapse
Affiliation(s)
- Sarah E Biehn
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, Ohio 43210, United States
| | - Patanachai Limpikirati
- Department of Food and Pharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand
| | - Richard W Vachet
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Steffen Lindert
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, Ohio 43210, United States
| |
Collapse
|
9
|
Tian Y, Bao Q, Wang N, Wan N, Lv L, Hao H, He C, Ye H. Time-Resolved Acetaldehyde-Based Accessibility Profiling Maps Ligand-Target Interactions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:519-530. [PMID: 33382614 DOI: 10.1021/jasms.0c00382] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Elucidating ligand-protein interactions is important in understanding the biochemical machinery for given proteins. Previously, formaldehyde (FH)-based labeling has been employed to obtain such structural knowledge, since reactive residues that participate in ligand-target interactions display reduced accessibility to FH-labeling reagents, and thus can be identified by quantitative proteomics. Although being rapid and efficient for probing proteinaceous lysine accessibility, here, we report an acetaldehyde (AcH)-labeling approach that complements with FH for probing ligand-target interactions. AcH labeling examines lysine accessibility at a more moderate reaction speed and hence delivers a cleaner reaction when compared to that of FH. The subsequent application of AcH to label RNase A without and with ligands has assisted to assign lysines involved in ligand-RNase A binding by detecting the time-dependent changes in accessibility profiles. We further employed multiple reaction monitoring (MRM) to quantify these ligand-binding-responsive sites when a variety of potential ligands were queried. We noted that the time-resolved abundance changes of these peptides can sensitively determine the ligand-binding sites and differentiate binding affinities among these ligands, which was confirmed by native mass spectrometry (MS) and molecular docking. Lastly, we demonstrated that the binding sites can be recognized by monitoring the chemical accessibility of these responsive peptides in cell lysates. Together, we believe that the proposed combined use of AcH-based lysine accessibility profiling, native MS, and MRM screening is a powerful toolbox in characterizing ligand-target interactions, mapping topography, and interrogating affinities and holds promise for future applications in a complex cellular environment.
Collapse
Affiliation(s)
- Yang Tian
- Department of Pharmacology, School of Pharmacy, China Pharmaceutical University, Tongjiaxiang #24, Nanjing, Jiangsu 210009, China
| | - Qiuyu Bao
- Jiangsu Provincial Key Laboratory of Drug Metabolism and Pharmacokinetics, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Tongjiaxiang #24, Nanjing, Jiangsu 210009, China
| | - Nian Wang
- Jiangsu Provincial Key Laboratory of Drug Metabolism and Pharmacokinetics, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Tongjiaxiang #24, Nanjing, Jiangsu 210009, China
| | - Ning Wan
- Jiangsu Provincial Key Laboratory of Drug Metabolism and Pharmacokinetics, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Tongjiaxiang #24, Nanjing, Jiangsu 210009, China
| | - Langlang Lv
- Jiangsu Provincial Key Laboratory of Drug Metabolism and Pharmacokinetics, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Tongjiaxiang #24, Nanjing, Jiangsu 210009, China
| | - Haiping Hao
- Jiangsu Provincial Key Laboratory of Drug Metabolism and Pharmacokinetics, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Tongjiaxiang #24, Nanjing, Jiangsu 210009, China
| | - Chaoyong He
- Department of Pharmacology, School of Pharmacy, China Pharmaceutical University, Tongjiaxiang #24, Nanjing, Jiangsu 210009, China
| | - Hui Ye
- Jiangsu Provincial Key Laboratory of Drug Metabolism and Pharmacokinetics, State Key Laboratory of Natural Medicines, China Pharmaceutical University, Tongjiaxiang #24, Nanjing, Jiangsu 210009, China
| |
Collapse
|