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Kaltashov IA, Bobst CE, Pawlowski J, Wang G. Mass spectrometry-based methods in characterization of the higher order structure of protein therapeutics. J Pharm Biomed Anal 2020; 184:113169. [PMID: 32092629 DOI: 10.1016/j.jpba.2020.113169] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 02/06/2020] [Accepted: 02/11/2020] [Indexed: 12/31/2022]
Abstract
Higher order structure of protein therapeutics is an important quality attribute, which dictates both potency and safety. While modern experimental biophysics offers an impressive arsenal of state-of-the-art tools that can be used for the characterization of higher order structure, many of them are poorly suited for the characterization of biopharmaceutical products. As a result, these analyses were traditionally carried out using classical techniques that provide relatively low information content. Over the past decade, mass spectrometry made a dramatic debut in this field, enabling the characterization of higher order structure of biopharmaceuticals as complex as monoclonal antibodies at a level of detail that was previously unattainable. At present, mass spectrometry is an integral part of the analytical toolbox across the industry, which is critical not only for quality control efforts, but also for discovery and development.
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Affiliation(s)
- Igor A Kaltashov
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, MA, USA.
| | - Cedric E Bobst
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, MA, USA
| | - Jake Pawlowski
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, MA, USA
| | - Guanbo Wang
- School of Chemistry and Materials Science, Nanjing Normal University, Nanjing, Jiangsu Province, PR China
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2
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Xiao Y, Li M, Larocque R, Zhang F, Malhotra A, Chen J, Linhardt RJ, Konermann L, Xu D. Dimerization interface of osteoprotegerin revealed by hydrogen-deuterium exchange mass spectrometry. J Biol Chem 2018; 293:17523-17535. [PMID: 30254073 DOI: 10.1074/jbc.ra118.004489] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 09/20/2018] [Indexed: 01/13/2023] Open
Abstract
Previous structural studies of osteoprotegerin (OPG), a crucial negative regulator of bone remodeling and osteoclastogenesis, were mostly limited to the N-terminal ligand-binding domains. It is now known that the three C-terminal domains of OPG also play essential roles in its function by mediating OPG dimerization, OPG-heparan sulfate (HS) interactions, and formation of the OPG-HS-receptor activator of nuclear factor κB ligand (RANKL) ternary complex. Employing hydrogen-deuterium exchange MS methods, here we investigated the structure of full-length OPG in complex with HS or RANKL in solution. Our data revealed two noteworthy aspects of the OPG structure. First, we found that the interconnection between the N- and C-terminal domains is much more rigid than previously thought, possibly because of hydrophobic interactions between the fourth cysteine-rich domain and the first death domain. Second, we observed that two hydrophobic clusters located in two separate C-terminal domains directly contribute to OPG dimerization, likely by forming a hydrophobic dimerization interface. Aided by site-directed mutagenesis, we further demonstrated that an intact dimerization interface is essential for the biological activity of OPG. Our study represents an important step toward deciphering the structure-function relationship of the full-length OPG protein.
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Affiliation(s)
- Yiming Xiao
- From the Department of Chemistry, University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Miaomiao Li
- the Department of Oral Biology, University of Buffalo, Buffalo, New York 14214, and
| | - Rinzhi Larocque
- the Department of Oral Biology, University of Buffalo, Buffalo, New York 14214, and
| | - Fuming Zhang
- the Department of Chemical and Biological Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180
| | - Anju Malhotra
- the Department of Chemical and Biological Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180
| | - Jianle Chen
- the Department of Chemical and Biological Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180
| | - Robert J Linhardt
- the Department of Chemical and Biological Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180
| | - Lars Konermann
- From the Department of Chemistry, University of Western Ontario, London, Ontario N6A 5B7, Canada,
| | - Ding Xu
- the Department of Oral Biology, University of Buffalo, Buffalo, New York 14214, and
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3
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Fast CS, Vahidi S, Konermann L. Changes in Enzyme Structural Dynamics Studied by Hydrogen Exchange-Mass Spectrometry: Ligand Binding Effects or Catalytically Relevant Motions? Anal Chem 2017; 89:13326-13333. [DOI: 10.1021/acs.analchem.7b03506] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Courtney S. Fast
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Siavash Vahidi
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Lars Konermann
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
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4
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Kumar S, Sharma D, Kumar R. Role of Macromolecular Crowding on Stability and Iron Release Kinetics of Serum Transferrin. J Phys Chem B 2017; 121:8669-8683. [PMID: 28837344 DOI: 10.1021/acs.jpcb.7b05702] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The macromolecular crowding influences the structural stability and functional properties of transferrin (Tf). The equilibrium as well as kinetic studies of Tf at different concentrations of crowding agents (dextran 40, dextran 70, and ficoll 70) and at a fixed concentration of dextran 40 under different concentrations of NaCl at pH 7.4 and 5.6 (±1) revealed that (i) the crowder environment increases the diferric-Tf (Fe2Tf) stability against iron loss and overall denaturation of the protein, (ii) both in the absence and presence of crowder, the presence of salt promotes the loss of iron and overall denaturation of Fe2Tf which is due to ionic screening of electrostatic interactions, (iii) the crowder environment retards iron release from monoferric N-lobe of Tf (FeNTf) by increasing enthalpic barrier, (iv) the retardation of iron release by crowding is enthalpically dominated than the entropic one, (v) both in the absence and presence of crowder, the presence of salt accelerates the iron release from FeNTf due to ionic screening of electrostatic interactions and anion binding to KISAB sites, and (vi) the crowders environment is unable to diminish (a) the salt-induced destabilization of Fe2Tf against the loss of iron and overall denaturation and (b) the anion effect and ionic screening of diffusive counterions responsible to promote iron release from FeNTf.
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Affiliation(s)
- Sandeep Kumar
- School of Chemistry and Biochemistry, Thapar University , Patiala 147004, India
| | - Deepak Sharma
- Council of Scientific and Industrial Research, Institute of Microbial Technology , Sector 39A, Chandigarh, India
| | - Rajesh Kumar
- Centre for Chemical Sciences, School of Bassic and Applied Sciences, Central University of Punjab , Bathinda 151001, India
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5
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Xiao Y, Shaw GS, Konermann L. Calcium-Mediated Control of S100 Proteins: Allosteric Communication via an Agitator/Signal Blocking Mechanism. J Am Chem Soc 2017; 139:11460-11470. [PMID: 28758397 DOI: 10.1021/jacs.7b04380] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Allosteric proteins possess dynamically coupled residues for the propagation of input signals to distant target binding sites. The input signals usually correspond to "effector is present" or "effector is not present". Many aspects of allosteric regulation remain incompletely understood. This work focused on S100A11, a dimeric EF-hand protein with two hydrophobic target binding sites. An annexin peptide (Ax) served as the target. Target binding is allosterically controlled by Ca2+ over a distance of ∼26 Å. Ca2+ promotes formation of a [Ca4 S100 Ax2] complex, where the Ax peptides are accommodated between helices III/IV and III'/IV'. Without Ca2+ these binding sites are closed, precluding interactions with Ax. The allosteric mechanism was probed by microsecond MD simulations in explicit water, complemented by hydrogen exchange mass spectrometry (HDX/MS). Consistent with experimental data, MD runs in the absence of Ca2+ and Ax culminated in target binding site closure. In simulations on [Ca4 S100] the target binding sites remained open. These results capture the essence of allosteric control, revealing how Ca2+ prevents binding site closure. Both HDX/MS and MD data showed that the metalation sites become more dynamic after Ca2+ loss. However, these enhanced dynamics do not represent the primary trigger of the allosteric cascade. Instead, a labile salt bridge acts as an incessantly active "agitator" that destabilizes the packing of adjacent residues, causing a domino chain of events that culminates in target binding site closure. This agitator represents the starting point of the allosteric signal propagation pathway. Ca2+ binding rigidifies elements along this pathway, thereby blocking signal transmission. This blocking mechanism does not conform to the commonly held view that allosteric communication pathways generally originate at the sites where effectors interact with the protein.
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Affiliation(s)
- Yiming Xiao
- Department of Chemistry, The University of Western Ontario , London, Ontario N6A 5B7, Canada
| | - Gary S Shaw
- Department of Chemistry, The University of Western Ontario , London, Ontario N6A 5B7, Canada
| | - Lars Konermann
- Department of Chemistry, The University of Western Ontario , London, Ontario N6A 5B7, Canada
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6
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Zhao H, Wang S, Nguyen SN, Elci SG, Kaltashov IA. Evaluation of Nonferrous Metals as Potential In Vivo Tracers of Transferrin-Based Therapeutics. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:211-9. [PMID: 26392277 PMCID: PMC4724545 DOI: 10.1007/s13361-015-1267-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 09/02/2015] [Accepted: 09/04/2015] [Indexed: 05/10/2023]
Abstract
Transferrin (Tf) is a promising candidate for targeted drug delivery. While development of such products is impossible without the ability to monitor biodistribution of Tf-drug conjugates in tissues and reliable measurements of their levels in blood and other biological fluids, the presence of very abundant endogenous Tf presents a significant impediment to such efforts. Several noncognate metals have been evaluated in this work as possible tracers of exogenous transferrin in complex biological matrices using inductively coupled plasma mass spectrometry (ICP MS) as a detection tool. Placing Ni(II) on a His-tag of recombinant Tf resulted in formation of a marginally stable protein-metal complex, which readily transfers the metal to ubiquitous physiological scavengers, such as serum albumin. An alternative strategy targeted iron-binding pockets of Tf, where cognate Fe(III) was replaced by metal ions known to bind this protein. Both Ga(III) and In(III) were evaluated, with the latter being vastly superior as a tracer (stronger binding to Tf unaffected by the presence of metal scavengers and the retained ability to associate with Tf receptor). Spiking serum with indium-loaded Tf followed by ICP MS detection demonstrated that protein quantities as low as 0.04 nM can be readily detected in animal blood. Combining laser ablation with ICP MS detection allows distribution of exogenous Tf to be mapped within animal tissue cross-sections with spatial resolution exceeding 100 μm. The method can be readily extended to a range of other therapeutics where metalloproteins are used as either carriers or payloads. Graphical Abstract ᅟ.
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Affiliation(s)
- Hanwei Zhao
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, MA, 01003, USA
| | - Shunhai Wang
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, MA, 01003, USA
| | - Son N Nguyen
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, MA, 01003, USA
| | - S Gokhan Elci
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, MA, 01003, USA
| | - Igor A Kaltashov
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, MA, 01003, USA.
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7
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Abdizadeh H, Atilgan AR, Atilgan C. Detailed molecular dynamics simulations of human transferrin provide insights into iron release dynamics at serum and endosomal pH. J Biol Inorg Chem 2015; 20:705-18. [DOI: 10.1007/s00775-015-1256-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 03/10/2015] [Indexed: 11/30/2022]
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8
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Sowole MA, Innes BT, Amunugama M, Litchfield DW, Brandl CJ, Shilton BH, Konermann L. Noncovalent binding of a cyclic peptide inhibitor to the peptidyl-prolyl isomerase Pin1, explored by hydrogen exchange mass spectrometry. CAN J CHEM 2015. [DOI: 10.1139/cjc-2014-0230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Pin1 is a peptidyl-prolyl isomerase (PPIase) that plays a central role in eukaryotic cell cycle regulation, making this protein an interesting target for cancer therapy. Pin1 exhibits high specificity for substrates where proline is preceded by phosphoserine or phosphothreonine. The protein comprises an N-terminal WW (tryptophan–tryptophan) domain and a C-terminal PPIase domain. The cyclic peptide [CRYPEVEIC] (square brackets are used to denote the cyclic structure) represents a lead compound for a new class of nonphosphorylated Pin1 inhibitors. Unfortunately, it has not been possible thus far to characterize the Pin1–[CRYPEVEIC] complex by X-ray crystallography. Thus, the exact binding mode remains unknown. The current work employs hydrogen/deuterium exchange mass spectrometry for gaining insights into the Pin1–[CRYPEVEIC] interactions. The WW domain shows extensive conformational dynamics, both in the presence and in the absence of ligand. In contrast, profound changes in deuteration kinetics are observed in the PPIase domain after the addition of [CRYPEVEIC]. The secondary structure elements β2, α3, and α4 exhibit markedly reduced deuteration, consistent with their postulated involvement in ligand binding. Unexpectedly, [CRYPEVEIC] destabilizes the range of residues 61–86, a segment that comprises basic side chains that normally interact with the substrate phosphate. This destabilization is likely caused by steric clashes with Y3 or E5 of the inhibitor. Ligand-induced destabilization has previously been reported for a few other proteins, but effects of this type are not very common. Our findings suggest that future crystallization trials on Pin1 variants deleted for residues in the 61–86 range might provide a path towards high-resolution X-ray structures of Pin1 bound to cyclic peptide inhibitors.
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Affiliation(s)
- Modupeola A. Sowole
- Department of Chemistry, The University of Western Ontario, London, ON N6A 5B7, Canada
| | - Brendan T. Innes
- Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A 5C1, Canada
| | - Mahasilu Amunugama
- Department of Chemistry, The University of Western Ontario, London, ON N6A 5B7, Canada
| | - David W. Litchfield
- Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A 5C1, Canada
| | - Christopher J. Brandl
- Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A 5C1, Canada
| | - Brian H. Shilton
- Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A 5C1, Canada
| | - Lars Konermann
- Department of Chemistry, The University of Western Ontario, London, ON N6A 5B7, Canada
- Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A 5C1, Canada
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9
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Sowole MA, Konermann L. Effects of Protein–Ligand Interactions on Hydrogen/Deuterium Exchange Kinetics: Canonical and Noncanonical Scenarios. Anal Chem 2014; 86:6715-22. [DOI: 10.1021/ac501849n] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Modupeola A. Sowole
- Department
of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Lars Konermann
- Department
of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
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10
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Electrostatic effects control the stability and iron release kinetics of ovotransferrin. J Biol Inorg Chem 2014; 19:1009-24. [DOI: 10.1007/s00775-014-1145-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Accepted: 04/29/2014] [Indexed: 10/25/2022]
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11
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Konermann L, Rodriguez AD, Sowole MA. Type 1 and Type 2 scenarios in hydrogen exchange mass spectrometry studies on protein–ligand complexes. Analyst 2014; 139:6078-87. [DOI: 10.1039/c4an01307g] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Ligand binding to a protein can elicit a wide range of responses when studied by HDX mass spectrometry.
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Affiliation(s)
- Lars Konermann
- Department of Chemistry
- The University of Western Ontario
- London, Canada
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12
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Abzalimov RR, Bobst CE, Kaltashov IA. A new approach to measuring protein backbone protection with high spatial resolution using H/D exchange and electron capture dissociation. Anal Chem 2013; 85:9173-80. [PMID: 23978257 DOI: 10.1021/ac401868b] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Inadequate spatial resolution remains one of the most serious limitations of hydrogen/deuterium exchange-mass spectrometry (HDX-MS), especially when applied to larger proteins (over 30 kDa). Supplementing proteolytic fragmentation of the protein in solution with ion dissociation in the gas phase has been used successfully by several groups to obtain near-residue level resolution. However, the restrictions imposed by the LC-MS/MS mode of operation on the data acquisition time frame makes it difficult in many cases to obtain a signal-to-noise ratio adequate for reliable assignment of the backbone amide protection levels at individual residues. This restriction is lifted in the present work by eliminating the LC separation step from the workflow and taking advantage of the high resolving power and dynamic range of a Fourier transform ion cyclotron resonance-mass spectrometer (FTICR-MS). A residue-level resolution is demonstrated for a peptic fragment of a 37 kDa recombinant protein (N-lobe of human serum transferrin), using electron-capture dissociation as an ion fragmentation tool. The absence of hydrogen scrambling in the gas phase prior to ion dissociation is verified using redundant HDX-MS data generated by FTICR-MS. The backbone protection pattern generated by direct HDX-MS/MS is in excellent agreement with the known crystal structure of the protein but also provides information on conformational dynamics, which is not available from the static X-ray structure.
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Affiliation(s)
- Rinat R Abzalimov
- Department of Chemistry, University of Massachusetts-Amherst , Amherst, MA 01003, United States
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Mass spectrometry study of a transferrin-based protein drug reveals the key role of protein aggregation for successful oral delivery. Proc Natl Acad Sci U S A 2012; 109:13544-8. [PMID: 22869744 DOI: 10.1073/pnas.1206924109] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A recently designed human growth hormone/transferrin fusion protein (GHT) remains one of the very few examples of a protein capable of eliciting measurable therapeutic response after oral administration. To better understand the underlying factors that resulted in this rare success of nonparenteral protein drug delivery, we analyzed proteolytic stability and receptor binding properties of this protein, the key factors in overcoming the primary barriers to successful oral delivery. Analysis of GHT by a combination of size exclusion chromatography and mass spectrometry revealed that a significant protein population exists in an oligomeric (GHTx) state in addition to the anticipated monomer (GHT1). These states of GHT were evaluated for their survivability in stomach-like conditions, as well as their ability to bind transferrin receptor (TfR). Our results reveal an exceptional stability of GHTx, as well as the preserved ability to bind TfR, a critical first step in crossing the epithelial-intestinal barrier through receptor-mediated transcytosis.
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14
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Kaltashov IA, Bobst CE, Abzalimov RR, Wang G, Baykal B, Wang S. Advances and challenges in analytical characterization of biotechnology products: mass spectrometry-based approaches to study properties and behavior of protein therapeutics. Biotechnol Adv 2012; 30:210-22. [PMID: 21619926 PMCID: PMC3176981 DOI: 10.1016/j.biotechadv.2011.05.006] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 04/13/2011] [Accepted: 05/09/2011] [Indexed: 12/19/2022]
Abstract
Biopharmaceuticals are a unique class of medicines due to their extreme structural complexity. The structure of these therapeutic proteins is critically important for their efficacy and safety, and the ability to characterize it at various levels (from sequence to conformation) is critical not only at the quality control stage, but also throughout the discovery and design stages. Biological mass spectrometry (MS) offers a variety of approaches to study structure and behavior of complex protein drugs and has already become a default tool for characterizing the covalent structure of protein therapeutics, including sequence and post-translational modifications. Recently, MS-based methods have also begun enjoying a dramatic growth in popularity as a means to provide information on higher order structure and dynamics of biotechnology products. In particular, hydrogen/deuterium exchange MS and charge state distribution analysis of protein ions in electrospray ionization (ESI) MS offer a convenient way to assess the integrity of protein conformation. Native ESI MS also allows the interactions of protein drugs with their therapeutic targets and other physiological partners to be monitored using simple model systems. MS-based methods are also applied to study pharmacokinetics of biopharmaceutical products, where they begin to rival traditional immunoassays. MS already provides valuable support to all stages of development of biopharmaceuticals, from discovery to post-approval monitoring, and its impact on the field of biopharmaceutical analysis will undoubtedly continue to grow.
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Affiliation(s)
- Igor A Kaltashov
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, MA, USA.
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15
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Kaltashov IA, Bobst CE, Zhang M, Leverence R, Gumerov DR. Transferrin as a model system for method development to study structure, dynamics and interactions of metalloproteins using mass spectrometry. Biochim Biophys Acta Gen Subj 2011; 1820:417-26. [PMID: 21726602 DOI: 10.1016/j.bbagen.2011.06.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Revised: 06/17/2011] [Accepted: 06/21/2011] [Indexed: 12/31/2022]
Abstract
BACKGROUND Transferrin (Tf) is a paradigmatic metalloprotein, which has been extensively studied in the past and still is a focal point of numerous investigation efforts owing to its unique role in iron homeostasis and enormous promise as a component of a wide range of therapies. SCOPE OF REVIEW Electrospray ionization mass spectrometry (ESI MS) is a potent analytical tool that has been used successfully to study various properties of Tf and Tf-based products, ranging from covalent structure and metal binding to conformation and interaction with their physiological partners. MAJOR CONCLUSIONS Various ESI MS-based techniques produce unique information on Tf properties and behavior that is highly complementary to information provided by other experimental techniques. GENERAL SIGNIFICANCE The experimental ESI MS-based techniques developed for Tf studies are not only useful for understanding of fundamental aspects of the iron-binding properties of this protein and optimizing Tf-based therapeutic products, but can also be applied to study a range of other metalloproteins. This article is part of a Special Issue entitled Transferrins: Molecular mechanisms of iron transport and disorders.
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Affiliation(s)
- Igor A Kaltashov
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, MA, USA.
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16
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Silva LP, Yu R, Calmettes C, Yang X, Moraes TF, Schryvers AB, Schriemer DC. Conserved interaction between transferrin and transferrin-binding proteins from porcine pathogens. J Biol Chem 2011; 286:21353-60. [PMID: 21487007 DOI: 10.1074/jbc.m111.226449] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Gram-negative porcine pathogens from the Pasteurellaceae family possess a surface receptor complex capable of acquiring iron from porcine transferrin (pTf). This receptor consists of transferrin-binding protein A (TbpA), a transmembrane iron transporter, and TbpB, a surface-exposed lipoprotein. Questions remain as to how the receptor complex engages pTf in such a way that iron is positioned for release, and whether divergent strains present distinct recognition sites on Tf. In this study, the TbpB-pTf interface was mapped using a combination of mass shift analysis and molecular docking simulations, localizing binding uniquely to the pTf C lobe for multiple divergent strains of Actinobacillus plueropneumoniae and suis. The interface was further characterized and validated with site-directed mutagenesis. Although targeting a common lobe, variants differ in preference for the two sublobes comprising the iron coordination site. Sublobes C1 and C2 participate in high affinity binding, but sublobe C1 contributes in a minor fashion to the overall affinity. Further, the TbpB-pTf complex does not release iron independent of other mediators, based on competitive iron binding studies. Together, our findings support a model whereby TbpB efficiently captures and presents iron-loaded pTf to other elements of the uptake pathway, even under low iron conditions.
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Affiliation(s)
- Leslie P Silva
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 1N4, Canada
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17
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Bobst CE, Thomas JJ, Salinas PA, Savickas P, Kaltashov IA. Impact of oxidation on protein therapeutics: conformational dynamics of intact and oxidized acid-β-glucocerebrosidase at near-physiological pH. Protein Sci 2011; 19:2366-78. [PMID: 20945356 DOI: 10.1002/pro.517] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The solution dynamics of an enzyme acid-β-glucocerebrosidase (GCase) probed at a physiologically relevant (lysosomal) pH by hydrogen/deuterium exchange mass spectrometry (HDX-MS) reveals very uneven distribution of backbone amide protection across the polypeptide chain. Highly mobile segments are observed even within the catalytic cavity alongside highly protective segments, highlighting the importance of the balance between conformational stability and flexibility for enzymatic activity. Forced oxidation of GCase that resulted in a 40-60% reduction in in vitro biological activity affects the stability of some key structural elements within the catalytic site. These changes in dynamics occur on a longer time scale that is irrelevant for catalysis, effectively ruling out loss of structure in the catalytic site as a major factor contributing to the reduction of the catalytic activity. Oxidation also leads to noticeable destabilization of conformation in remote protein segments on a much larger scale, which is likely to increase the aggregation propensity of GCase and affect its bioavailability. Therefore, it appears that oxidation exerts its negative impact on the biological activity of GCase indirectly, primarily through accelerated aggregation and impaired trafficking.
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Affiliation(s)
- Cedric E Bobst
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, Massachusetts 01003, USA
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18
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Ling JML, Shima CH, Schriemer DC, Schryvers AB. Delineating the regions of human transferrin involved in interactions with transferrin binding protein B from Neisseria meningitidis. Mol Microbiol 2010; 77:1301-14. [DOI: 10.1111/j.1365-2958.2010.07289.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Noncanonical interactions between serum transferrin and transferrin receptor evaluated with electrospray ionization mass spectrometry. Proc Natl Acad Sci U S A 2010; 107:8123-8. [PMID: 20404192 DOI: 10.1073/pnas.0914898107] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The primary route of iron acquisition in vertebrates is the transferrin receptor (TfR) mediated endocytotic pathway, which provides cellular entry to the metal transporter serum transferrin (Tf). Despite extensive research efforts, complete understanding of Tf-TfR interaction mechanism is still lacking owing to the complexity of this system. Electrospray ionization mass spectrometry (ESI MS) is used in this study to monitor the protein/receptor interaction and demonstrate the ability of metal-free Tf to associate with TfR at neutral pH. A set of Tf variants is used in a series of competition and displacement experiments to bracket TfR affinity of apo-Tf at neutral pH (0.2-0.6 microM). Consistent with current models of endosomal iron release from Tf, acidification of the protein solution results in a dramatic change of binding preferences, with apo-Tf becoming a preferred receptor binder. Contrary to the current models implying that the apo-Tf/TfR complex dissociates almost immediately upon exposure to the neutral environment at the cell surface, our data indicate that this complex remains intact. Iron-loaded Tf displaces apo-Tf from TfR, making it available for the next cycle of iron binding, transport and delivery to tissues. However, apo-Tf may still interfere with the cellular uptake of engineered Tf molecules whose TfR affinity is affected by various modifications (e.g., conjugation to cytotoxic molecules). This work also highlights the great potential of ESI MS as a tool capable of providing precise details of complex protein-receptor interactions under conditions that closely mimic the environment in which these encounters occur in physiological systems.
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Kaltashov IA, Bobst CE, Abzalimov RR, Berkowitz SA, Houde D. Conformation and dynamics of biopharmaceuticals: transition of mass spectrometry-based tools from academe to industry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2010; 21:323-37. [PMID: 19963397 PMCID: PMC2827695 DOI: 10.1016/j.jasms.2009.10.013] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2009] [Revised: 10/16/2009] [Accepted: 10/20/2009] [Indexed: 05/12/2023]
Abstract
Mass spectrometry plays a very visible role in biopharmaceutical industry, although its use in development, characterization, and quality control of protein drugs is mostly limited to the analysis of covalent structure (amino acid sequence and post-translational modifications). Despite the centrality of protein conformation to biological activity, stability, and safety of biopharmaceutical products, the expanding arsenal of mass spectrometry-based methods that are currently available to probe higher order structure and conformational dynamics of biopolymers did not, until recently, enjoy much attention in the industry. This is beginning to change as a result of recent work demonstrating the utility of these experimental tools for various aspects of biopharmaceutical product development and manufacturing. In this work, we use a paradigmatic protein drug interferon beta-1a as an example to illustrate the utility of mass spectrometry as a powerful tool not only to assess the integrity of higher order structure of a protein drug, but also to predict consequences of its degradation at a variety of levels.
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Affiliation(s)
- Igor A Kaltashov
- Department of Chemistry, University of Massachusetts-Amherst, Amherst, Massachusetts 01003, USA.
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