1
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Watts E, Bashyal A, Dunham SD, Crittenden CM, Brodbelt JS. Enhanced Characterization of Lysine-Linked Antibody Drug Conjugates Enabled by Middle-Down Mass Spectrometry and Higher-Energy Collisional Dissociation-Triggered Electron-Transfer/Higher-Energy Collisional Dissociation and Ultraviolet Photodissociation. Antibodies (Basel) 2024; 13:30. [PMID: 38651410 PMCID: PMC11036284 DOI: 10.3390/antib13020030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 04/02/2024] [Accepted: 04/11/2024] [Indexed: 04/25/2024] Open
Abstract
As the development of new biotherapeutics advances, increasingly sophisticated tandem mass spectrometry methods are needed to characterize the most complex molecules, including antibody drug conjugates (ADCs). Lysine-linked ADCs, such as trastuzumab-emtansine (T-DM1), are among the most heterogeneous biotherapeutics. Here, we implement a workflow that combines limited proteolysis with HCD-triggered EThcD and UVPD mass spectrometry for the characterization of the resulting middle-down large-sized peptides of T-DM1. Fifty-three payload-containing peptides were identified, ranging in mass from 1.8 to 16.9 kDa, and leading to the unambiguous identification of 46 out of 92 possible conjugation sites. In addition, seven peptides were identified containing multiple payloads. The characterization of these types of heterogeneous peptides represents an important step in unraveling the combinatorial nature of lysine-conjugated ADCs.
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Affiliation(s)
- Eleanor Watts
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712, USA; (E.W.); (A.B.)
| | - Aarti Bashyal
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712, USA; (E.W.); (A.B.)
| | - Sean D. Dunham
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712, USA; (E.W.); (A.B.)
| | | | - Jennifer S. Brodbelt
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712, USA; (E.W.); (A.B.)
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2
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Crittenden CM, Lanzillotti MB, Chen B. Top-Down Mass Spectrometry of Synthetic Single Guide Ribonucleic Acids Enabled by Facile Sample Clean-Up. Anal Chem 2023; 95:3180-3186. [PMID: 36606446 DOI: 10.1021/acs.analchem.2c03030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
In recent years, CRISPR-Cas9 genome editing has become an important technology in biomedical research and has demonstrated tremendous therapeutic potential. With Cas9 endonuclease, the use of single guide ribonucleic acids (sgRNAs) allows for sequence-specific cutting on target double-stranded deoxyribonucleic acids. Therefore, the design and quality of sgRNAs can greatly affect the efficiency and specificity of genome editing. Mass spectrometry (MS) has been a powerful tool to detect molecular features and sequence a variety of biomolecules; however, as the sizes of oligonucleotides get larger, it becomes more challenging to desalt samples and achieve high-quality intact spectra with effective fragmentation. Here, we develop a simple but effective online column-based clean-up method (reversed-phase column in a size exclusion mode) that removes formulation salts and metal adducts from larger oligonucleotides upon entering the mass spectrometer in a consistent manner. Using the top-down approach without any nuclease digestion, we characterized and sequenced 100-nucleotide-long sgRNAs by higher-energy collision dissociation (HCD), collision-induced dissociation (CID), ultraviolet photodissociation (UVPD), and activated electron photodetachment (a-EPD). In a single 10 min liquid chromatography-tandem MS (LC-MS/MS) run, CID yielded the best sequence coverage, of 67%. When adding complementary UVPD and a-EPD runs, we achieved 80% overall sequence coverage and 100% cleavages for the variable sequence, the first 20 nucleotides from the 5' end. This LC-MS/MS platform provides a facile top-down workflow to analyze and sequence larger chemically modified oligonucleotides with no sample treatment.
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Affiliation(s)
- Christopher M Crittenden
- Small Molecule Analytical Chemistry, Genentech Inc., South San Francisco, California 94080, United States
| | | | - Bifan Chen
- Small Molecule Analytical Chemistry, Genentech Inc., South San Francisco, California 94080, United States
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3
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Koenig SG, Angelaud R, Crittenden CM, Kurita K, Russell DJ, Marcoux JF, Matt T, Gosselin F. Development of Dual Practical Manufacturing Routes to Cognate Pyrrolobenzodiazepine-Based Linker-Drugs. Org Process Res Dev 2022. [DOI: 10.1021/acs.oprd.2c00129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Stefan G. Koenig
- Department of Small Molecule Process Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Rémy Angelaud
- Department of Small Molecule Process Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Christopher M. Crittenden
- Department of Small Molecule Analytical Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Kenji Kurita
- Department of Small Molecule Analytical Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - David J. Russell
- Department of Small Molecule Analytical Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
| | - Jean-Francois Marcoux
- Department of Manufacturing and Science Technology, F. Hoffmann-La Roche Ltd, Viaduktstrasse 31, 4051 Basel, Switzerland
| | - Thomas Matt
- Chemical R&D Department, Cerbios Pharma SA, Via Figino 6, 6917 Barbengo/Lugano, Switzerland
| | - Francis Gosselin
- Department of Small Molecule Process Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States
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4
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Goyon A, Scott B, Crittenden CM, Zhang K. Analysis of pharmaceutical drug oligomers by selective comprehensive two-dimensional liquid chromatography-high resolution mass spectrometry. J Pharm Biomed Anal 2022; 208:114466. [PMID: 34808518 DOI: 10.1016/j.jpba.2021.114466] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 10/04/2021] [Accepted: 11/02/2021] [Indexed: 11/17/2022]
Abstract
The presence of oligomeric impurities in drugs is often overlooked and less studied due to conventional small molecule analytical methods which are often not capable of capturing these oligomers. In the present work, the oligomer species of a lipophilic active pharmaceutical ingredient (API) containing an azetidine ring was investigated. No separation was observed by reversed-phase liquid chromatography (RPLC) methods, and only a partial separation of oligomer peaks was achieved by a size exclusion chromatography (SEC) method. To improve the resolution of the different oligomers species and understand the root cause of the formation of the oligomers, a selective comprehensive two-dimensional liquid chromatography (2D-LC) method was developed by coupling SEC to RPLC. The selective comprehensive SEC × RPLC method allowed the separation of 16 species and evidenced four main groups of oligomer impurities. The contour plots of 3 API lots helped to visualize the oligomer profiles and quickly compare the difference between these lots. Finally, the oligomer peaks separated by 2D-LC were identified by high-resolution mass spectrometry (HRMS) using a Q Exactive mass spectrometer. The developed 2D-LC/HRMS workflow provides a fast and generic screening approach to quickly examine and visualize the oligomeric impurities in API materials, and direct the impurity control strategy during process development.
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Affiliation(s)
- Alexandre Goyon
- Small Molecule Analytical Chemistry, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Brandon Scott
- Small Molecule Analytical Chemistry, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Christopher M Crittenden
- Small Molecule Analytical Chemistry, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Kelly Zhang
- Small Molecule Analytical Chemistry, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA.
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5
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Chen B, Kurita KL, Wong N, Crittenden CM. Ultraviolet photodissociation facilitates mass spectrometry-based structure elucidation with pyrrolidine and piperidine containing compounds. J Pharm Biomed Anal 2022; 211:114622. [DOI: 10.1016/j.jpba.2022.114622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 01/22/2022] [Accepted: 01/24/2022] [Indexed: 11/27/2022]
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6
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Goyon A, Scott B, Kurita K, Crittenden CM, Shaw D, Lin A, Yehl P, Zhang K. Full Sequencing of CRISPR/Cas9 Single Guide RNA (sgRNA) via Parallel Ribonuclease Digestions and Hydrophilic Interaction Liquid Chromatography-High-Resolution Mass Spectrometry Analysis. Anal Chem 2021; 93:14792-14801. [PMID: 34699173 DOI: 10.1021/acs.analchem.1c03533] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
CRISPR/Cas9 is a powerful genome editing approach in which a Cas9 enzyme and a single guide RNA (sgRNA) form a ribonucleoprotein complex effectively targeting site-specific cleavages of DNA. Accurate sequencing of sgRNA is critical to patient safety and is the expectation by regulatory agencies. In this paper, we present the full sequencing of sgRNA via parallel ribonuclease (RNase) T1, A, and U2 digestions and the simultaneous separation and identification of the digestion products by hydrophilic interaction liquid chromatography (HILIC) coupled to high-resolution mass spectrometry (HRMS). When using RNase T1 digestion alone, a maximal sequence coverage of 81% was obtained excluding the nonunique fragments. Full sgRNA sequencing was achieved using unique fragments generated by RNase T1, A, and U2 parallel digestions. Thorough optimization of sgRNA digestions was performed by varying the nuclease-to-sgRNA ratio, buffer conditions, and reaction times. A biocompatible ethylene-bridged hybrid amide column was evaluated for the separation of RNase digestion products. To our knowledge, it is the first time that (i) RNA digests are separated and identified by HILIC-HRMS and (ii) chemically modified sgRNAs are directly sequenced via a bottom-up approach.
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Affiliation(s)
- Alexandre Goyon
- Small Molecule Analytical Chemistry, 1 DNA Way, South San Francisco, California 94080, United States
| | - Brandon Scott
- Small Molecule Analytical Chemistry, 1 DNA Way, South San Francisco, California 94080, United States
| | - Kenji Kurita
- Small Molecule Analytical Chemistry, 1 DNA Way, South San Francisco, California 94080, United States
| | - Christopher M Crittenden
- Small Molecule Analytical Chemistry, 1 DNA Way, South San Francisco, California 94080, United States
| | - David Shaw
- Cell Therapy Engineering and Development, 1 DNA Way, South San Francisco, California 94080, United States
| | - Andy Lin
- Technical Development Project and Portfolio Management Genentech, 1 DNA Way, South San Francisco, California 94080, United States
| | - Peter Yehl
- Small Molecule Analytical Chemistry, 1 DNA Way, South San Francisco, California 94080, United States
| | - Kelly Zhang
- Small Molecule Analytical Chemistry, 1 DNA Way, South San Francisco, California 94080, United States
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7
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Crittenden CM, DiPasquale AG. Two crystallographic forms and the absolute structure of 5α,14α-androstane. Acta Crystallogr C Struct Chem 2021; 77:537-543. [PMID: 34482297 DOI: 10.1107/s2053229621008408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 08/12/2021] [Indexed: 11/10/2022]
Abstract
5α,14α-Androstane (C19H32) crystallizes in two different polymorphic forms in the same vapor diffusion experiment. The major form (Form I) crystallizes as thin plates in the space group P21, with Z = 4. These plates are twinned along a long c axis of length 43 Å and readily suffer from radiation damage when diffracted. The minor form (Form II) crystallizes as fine needles in the space group P212121, Z = 3. In the minor form, 5α,14α-androstane cocrystallizes with 5α,14α-androstan-17-one, an oxidation product of 5α,14α-androstane. The presence of 5α,14α-androstan-17-one in the minor form of the crystals was confirmed by HR-MS. Form II can be crystallized as a pure form without the ketone impurity using a different solvent system. High level density functional theory (DFT) lattice free energy calculations were performed and show that both pure forms are isoergic within the estimated error of the calculations.
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Affiliation(s)
- Christopher M Crittenden
- Small Molecule Pharmaceutical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Antonio G DiPasquale
- Small Molecule Pharmaceutical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA
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8
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Chen T, Tang S, Hecht ES, Yen CW, Andersen N, Chin S, Cadang L, Roper B, Estevez A, Rohou A, Chang D, Dai L, Liu P, Al-Sayah M, Nagapudi K, Lin F, Famili A, Hu C, Kuhn R, Stella C, Crittenden CM, Gruenhagen JA, Venkatramani C, Hannoush RN, Leung D, Vandlen R, Yehl P. Discovery of a dual pathway aggregation mechanism for a therapeutic constrained peptide. J Pharm Sci 2021; 110:2362-2371. [PMID: 33652014 DOI: 10.1016/j.xphs.2020.12.041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 12/07/2020] [Indexed: 10/22/2022]
Abstract
Constrained peptides (CPs) have emerged as attractive candidates for drug discovery and development. To fully unlock the therapeutic potential of CPs, it is crucial to understand their physical stability and minimize the formation of aggregates that could induce immune responses. Although amyloid like aggregates have been researched extensively, few studies have focused on aggregates from other peptide scaffolds (e.g., CPs). In this work, a streamlined approach to effectively profile the nature and formation pathway of CP aggregates was demonstrated. Aggregates of various sizes were detected and shown to be amorphous. Though no major changes were found in peptide structure upon aggregation, these aggregates appeared to have mixed natures, consisting of primarily non-covalent aggregates with a low level of covalent species. This co-existence phenomenon was also supported by two kinetic pathways observed in time- and temperature-dependent aggregation studies. Furthermore, a stability study with 8 additional peptide variants exhibited good correlation between aggregation propensity and peptide hydrophobicity. Therefore, a dual aggregation pathway was proposed, with the non-covalent aggregates driven by hydrophobic interactions, whereas the covalent ones formed through disulfide scrambling. Overall, the workflow presented here provides a powerful strategy for comprehensive characterization of peptide aggregates and understanding their mechanisms of formation.
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Affiliation(s)
- Tao Chen
- Small Molecule Pharmaceutical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States.
| | - Shijia Tang
- Small Molecule Pharmaceutical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Elizabeth S Hecht
- Department of Microchemistry, Proteomics, and Lipidomics, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Chun-Wan Yen
- Small Molecule Pharmaceutical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Nisana Andersen
- Protein Analytical Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Steven Chin
- Small Molecule Pharmaceutical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Lance Cadang
- Protein Analytical Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Brian Roper
- Protein Analytical Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Alberto Estevez
- Department of Structural Biology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Alexis Rohou
- Department of Structural Biology, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Debby Chang
- Department of Drug Delivery, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Lu Dai
- Protein Analytical Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Peter Liu
- Department of Microchemistry, Proteomics, and Lipidomics, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Mohammad Al-Sayah
- Small Molecule Pharmaceutical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Karthik Nagapudi
- Small Molecule Pharmaceutical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Fiona Lin
- Small Molecule Pharmaceutical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Amin Famili
- Small Molecule Pharmaceutical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Chloe Hu
- Small Molecule Pharmaceutical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Robert Kuhn
- Small Molecule Pharmaceutical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Cinzia Stella
- Protein Analytical Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Christopher M Crittenden
- Small Molecule Pharmaceutical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Jason A Gruenhagen
- Small Molecule Pharmaceutical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Cadapakam Venkatramani
- Small Molecule Pharmaceutical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Rami N Hannoush
- Department of Early Discovery Biochemistry, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Dennis Leung
- Small Molecule Pharmaceutical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Richard Vandlen
- Department of Protein Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
| | - Peter Yehl
- Small Molecule Pharmaceutical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States
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9
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Chin S, Chen T, Hannoush RN, Crittenden CM. Tracking internal and external ions for constrained peptides leads to enhanced sequence coverage and disulfide bond deciphering. J Pharm Biomed Anal 2021; 195:113893. [PMID: 33445001 DOI: 10.1016/j.jpba.2021.113893] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 12/30/2020] [Accepted: 01/02/2021] [Indexed: 10/22/2022]
Abstract
Top-down characterization of disulfide-rich peptides and proteins presents many challenges due to the constrained and protected amino acid backbone. Typically, chemical reduction is required to reduce the disulfide bonds and/or enzymatic digestion (bottom-up analysis) is utilized to selectively cleave the amino acid sequence prior to mass spectrometry analysis owing to the challenges associated with intact, top-down analysis of these biomolecules. While extravagant top-down characterization techniques such as ultraviolet photodissociation (UVPD) or electron capture dissociation (ECD), have demonstrated the ability to break disulfide bonds in top-down workflows, implementation of these technologies and analysis of the resulting fragmentation spectra is not trivial and often inaccessible to many laboratories and users. In the study presented herein, traditional collision induced dissociation (CID) of disulfide-rich peptides is performed to confirm the disulfide bond connectivity and localize chemical modifications for these synthetic therapeutic peptides. While collisional activation does not fragment the peptide backbone linearly (typical N- and C-terminal fragment ions) within the disulfide-bonded regions, internal and external ions are consistently produced throughout the sequence via secondary fragmentation pathways. In this study, seven disulfide-rich peptides (Peptides A - G) with similar disulfide connectivity but varying amino acid composition were subjected to collisional activation for sequencing and disulfide bond confirmation. While only four linear b- and y-type fragment ions are produced for these peptides, fragmentation throughout the amino acid sequence is observed when searching for internal and external fragment ions. These ions are typically not considered during traditional top-down sequencing experiments due to the computational challenge of having an increased search space for fragment ion identification. Through the identification of reproducible internal and external fragment ions, site-specific modifications can also be localized, such as oxidation on the 18th residue in Peptide A. Ultimately, this observation and identification of internal and external ions simplifies the experimental process and wet-chemistry required to accurately depict the disulfide connectivity and the sequencing of these traditionally challenging biomolecules. Further consideration to these non-traditional fragment ions should be given during top-down intact peptide and protein analysis, especially when non-linear sequences are involved.
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Affiliation(s)
- Steven Chin
- Small Molecule Analytical Chemistry, Genentech Inc., South San Francisco, CA, 94080, United States
| | - Tao Chen
- Small Molecule Analytical Chemistry, Genentech Inc., South San Francisco, CA, 94080, United States
| | - Rami N Hannoush
- Department of Early Discovery Biochemistry, Genentech Inc., South San Francisco, CA, 94080, United States
| | - Christopher M Crittenden
- Small Molecule Analytical Chemistry, Genentech Inc., South San Francisco, CA, 94080, United States.
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10
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Crittenden CM, Novelli ET, Mehaffey MR, Xu GN, Giles DH, Fies WA, Dalby KN, Webb LJ, Brodbelt JS. Structural Evaluation of Protein/Metal Complexes via Native Electrospray Ultraviolet Photodissociation Mass Spectrometry. J Am Soc Mass Spectrom 2020; 31:1140-1150. [PMID: 32275426 PMCID: PMC7386362 DOI: 10.1021/jasms.0c00066] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Ultraviolet photodissociation (UVPD) has emerged as a promising tool to characterize proteins with regard to not only their primary sequences and post-translational modifications, but also their tertiary structures. In this study, three metal-binding proteins, Staphylococcal nuclease, azurin, and calmodulin, are used to demonstrate the use of UVPD to elucidate metal-binding regions via comparisons between the fragmentation patterns of apo (metal-free) and holo (metal-bound) proteins. The binding of staphylococcal nuclease to calcium was evaluated, in addition to a series of lanthanide(III) ions which are expected to bind in a similar manner as calcium. On the basis of comparative analysis of the UVPD spectra, the binding region for calcium and the lanthanide ions was determined to extend from residues 40-50, aligning with the known crystal structure. Similar analysis was performed for both azurin (interrogating copper and silver binding) and calmodulin (four calcium binding sites). This work demonstrates the utility of UVPD methods for determining and analyzing the metal binding sites of a variety of classes of proteins.
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Affiliation(s)
| | - Elisa T Novelli
- Department of Chemistry, University of Texas, Austin, Texas 78712, United States
| | - M Rachel Mehaffey
- Department of Chemistry, University of Texas, Austin, Texas 78712, United States
| | - Gulan N Xu
- Department of Chemistry, University of Texas, Austin, Texas 78712, United States
| | - David H Giles
- Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, Texas 78712, United States
| | - Whitney A Fies
- Department of Chemistry, University of Texas, Austin, Texas 78712, United States
| | - Kevin N Dalby
- Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, Texas 78712, United States
- Graduate Program in Cell and Molecular Biology, University of Texas, Austin, Texas 78712, United States
| | - Lauren J Webb
- Department of Chemistry, University of Texas, Austin, Texas 78712, United States
- Institute for Cell and Molecular Biology, University of Texas, Austin, Texas 78712, United States
- Texas Materials Institute, University of Texas, Austin, Texas 78712, United States
| | - Jennifer S Brodbelt
- Department of Chemistry, University of Texas, Austin, Texas 78712, United States
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11
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Blevins MS, Kim D, Crittenden CM, Hong S, Yeh HC, Petty JT, Brodbelt JS. Footprints of Nanoscale DNA-Silver Cluster Chromophores via Activated-Electron Photodetachment Mass Spectrometry. ACS Nano 2019; 13:14070-14079. [PMID: 31755695 PMCID: PMC7047740 DOI: 10.1021/acsnano.9b06470] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
DNA-templated silver clusters (AgC) are fluorescent probes and biosensors whose electronic spectra can be tuned by their DNA hosts. However, the underlying rules that relate DNA sequence and structure to DNA-AgC fluorescence and photophysics are largely empirical. Here, we employ 193 nm activated electron photodetachment (a-EPD) mass spectrometry as a hybrid MS3 approach to gain structural insight into these nanoscale chromophores. Two DNA-AgC systems are investigated with a 20 nt single-stranded DNA (ssDNA) and a 28 nt hybrid hairpin/single-stranded DNA (hpDNA). Both oligonucleotides template Ag10 clusters, but the two complexes are distinct chromophores: the former has a violet absorption at 400 nm with no observable emission, while the latter has a blue-green absorption at 490 nm with strong green emission at 550 nm. Via identification of both apo and holo (AgC-containing) sequence ions generated upon a-EPD and mapping areas of sequence dropout, specific DNA regions that encapsulate the AgC are assigned and attributed to the coordination with the DNA nucleobases. These a-EPD footprints are distinct for the two complexes. The ssDNA contacts the cluster via four nucleobases (CCTT) in the central region of the strand, whereas the hpDNA coordinates the cluster via 13 nucleobases (TTCCCGCCTTTTG) in the double-stranded region of the hairpin. This difference is consistent with prior X-ray scattering spectra and suggests that the clusters can adapt to different DNA hosts. More importantly, the a-EPD footprints directly identify the nucleobases that are in direct contact with the AgC. As these contacting nucleobases can tune the electronic structures of the Ag core and protect the AgC from collisional quenching in solution, understanding the DNA-silver contacts within these complexes will facilitate future biosensor designs.
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Affiliation(s)
- Molly S. Blevins
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Dahye Kim
- Department of Chemistry, Furman University, Greenville, South Carolina 29613, United States
| | | | - Soonwoo Hong
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas 78712, United States
| | - Hsin-Chih Yeh
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas 78712, United States
- Texas Materials Institute, University of Texas at Austin, Austin, Texas 78712, United States
| | - Jeffrey T. Petty
- Department of Chemistry, Furman University, Greenville, South Carolina 29613, United States
| | - Jennifer S. Brodbelt
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
- Corresponding Author:.
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12
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Crittenden CM, Escobar EE, Williams PE, Sanders JD, Brodbelt JS. Characterization of Antigenic Oligosaccharides from Gram-Negative Bacteria via Activated Electron Photodetachment Mass Spectrometry. Anal Chem 2019; 91:4672-4679. [PMID: 30844257 DOI: 10.1021/acs.analchem.9b00048] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Lipooligosaccharides (LOS), composed of hydrophilic oligosaccharides and hydrophobic lipid A domains, are found on the outer membranes of Gram-negative bacteria. Here we report the characterization of deacylated LOS of LPS by activated-electron photodetachment mass spectrometry. Collision induced dissociation (CID) of these phosphorylated oligosaccharides produces simple MS/MS spectra with most fragment ions arising from cleavages near the reducing end of the molecule where the phosphate groups are located. In contrast, 193 nm ultraviolet photodissociation (UVPD) generates a wide array of product ions throughout the oligosaccharide including cross-ring fragments that illuminate the branching patterns. However, there are also product ions that are redundant or uninformative, resulting in more congested spectra that complicate interpretation. In this work, a hybrid UVPD-CID approach known as activated-electron photodetachment (a-EPD) affords less congested spectra than UVPD alone and richer fragmentation patterns than CID alone. a-EPD combines UVPD of negatively charged oligosaccharides to yield abundant charge-reduced radical ions which are subsequently interrogated by collisional activation. CID of the charge-reduced precursors results in extensive fragmentation throughout the backbone of the oligosaccharide. This hybridized a-EPD approach was employed to characterize the structure and branching pattern of deacylated LOS of E. coli.
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Affiliation(s)
| | - Edwin E Escobar
- Department of Chemistry , University of Texas at Austin , Austin , Texas 78712 , United States
| | - Peggy E Williams
- Department of Chemistry , University of Texas at Austin , Austin , Texas 78712 , United States
| | - James D Sanders
- Department of Chemistry , University of Texas at Austin , Austin , Texas 78712 , United States
| | - Jennifer S Brodbelt
- Department of Chemistry , University of Texas at Austin , Austin , Texas 78712 , United States
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13
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Simoska O, Sans M, Fitzpatrick MD, Crittenden CM, Eberlin LS, Shear JB, Stevenson KJ. Real-Time Electrochemical Detection of Pseudomonas aeruginosa Phenazine Metabolites Using Transparent Carbon Ultramicroelectrode Arrays. ACS Sens 2019; 4:170-179. [PMID: 30525472 DOI: 10.1021/acssensors.8b01152] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Here, we use a recently developed electrochemical sensing platform of transparent carbon ultramicroelectrode arrays (T-CUAs) for the in vitro detection of phenazine metabolites from the opportunistic human pathogen Pseudomonas aeruginosa. Specifically, redox-active metabolites pyocyanin (PYO), 5-methylphenazine-1-carboxylic acid (5-MCA), and 1-hydroxyphenazine (OHPHZ) are produced by P. aeruginosa, which is commonly found in chronic wound infections and in the lungs of cystic fibrosis patients. As highly diffusible chemicals, PYO and other metabolites are extremely toxic to surrounding host cells and other competing microorganisms, thus their detection is of great importance as it could provide insights regarding P. aeruginosa virulence mechanisms. Phenazine metabolites are known to play important roles in cellular functions; however, very little is known about how their concentrations fluctuate and influence cellular behaviors over the course of infection and growth. Herein we report the use of easily assembled, low-cost electrochemical sensors that provide rapid response times, enhanced sensitivity, and high reproducibility. As such, these T-CUAs enable real-time electrochemical monitoring of PYO and another extremely reactive and distinct redox-active phenazine metabolite, 5-methylphenazine-1-carboxylic acid (5-MCA), from a highly virulent laboratory P. aeruginosa strain, PA14. In addition to quantifying phenazine metabolite concentrations, changes in phenazine dynamics are observed in the biosynthetic route for the production of PYO. Our quantitative results, over a 48-h period, show increasing PYO concentrations during the first 21 h of bacterial growth, after which PYO levels plateau and then slightly decrease. Additionally, we explore environmental effects on phenazine dynamics and PYO concentrations in two growth media, tryptic soy broth (TSB) and lysogeny broth (LB). The maximum concentrations of cellular PYO were determined to be 190 ± 5 μM and 150 ± 1 μM in TSB and LB, respectively. Finally, using desorption electrospray ionization (DESI) and nanoelectrospray ionization (nano-ESI) mass spectrometry we confirm the detection and identification of reactive phenazine metabolites.
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Affiliation(s)
- Olja Simoska
- Department of Chemistry, University of Texas at Austin, 1 University Station, Stop A5300, Austin, Texas 78712, United States
| | - Marta Sans
- Department of Chemistry, University of Texas at Austin, 1 University Station, Stop A5300, Austin, Texas 78712, United States
| | - Mignon D. Fitzpatrick
- Department of Chemistry, University of Texas at Austin, 1 University Station, Stop A5300, Austin, Texas 78712, United States
| | - Christopher M. Crittenden
- Department of Chemistry, University of Texas at Austin, 1 University Station, Stop A5300, Austin, Texas 78712, United States
| | - Livia S. Eberlin
- Department of Chemistry, University of Texas at Austin, 1 University Station, Stop A5300, Austin, Texas 78712, United States
| | - Jason B. Shear
- Department of Chemistry, University of Texas at Austin, 1 University Station, Stop A5300, Austin, Texas 78712, United States
| | - Keith J. Stevenson
- Center for Electrochemical Energy Storage, Skolkovo Institute of Science and Technology, 3 Nobel Street, Moscow 143026, Russia
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14
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Parsley NC, Kirkpatrick CL, Crittenden CM, Rad JG, Hoskin DW, Brodbelt JS, Hicks LM. PepSAVI-MS reveals anticancer and antifungal cycloviolacins in Viola odorata. Phytochemistry 2018; 152:61-70. [PMID: 29734037 PMCID: PMC6003877 DOI: 10.1016/j.phytochem.2018.04.014] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 04/12/2018] [Accepted: 04/24/2018] [Indexed: 05/07/2023]
Abstract
Widespread resistance to antimicrobial and cancer therapeutics is evolving in every country worldwide and has a direct impact on global health, agriculture and the economy. The specificity and selectivity of bioactive peptide natural products present a possible stopgap measure to address the ongoing deficit of new therapeutic compounds. PepSAVI-MS (Statistically-guided bioActive Peptides prioritized VIa Mass Spectrometry) is an adaptable method for the analysis of natural product libraries to rapidly identify bioactive peptides. This pipeline was validated via screening of the cyclotide-rich botanical species Viola odorata and identification of the known antimicrobial and anticancer cyclotide cycloviolacin O2. Herein we present and validate novel bioactivities of the anthelmintic V. odorata cyclotide, cycloviolacin O8 (cyO8), including micromolar anticancer activity against PC-3 prostate, MDA-MB-231 breast, and OVCAR-3 ovarian cancer cell lines and antifungal activity against the agricultural pathogen Fusarium graminearum. A reduction/alkylation strategy in tandem with PepSAVI-MS analysis also revealed several previously uncharacterized putatively bioactive cyclotides. Downstream implementation of ultraviolet photodissociation (UVPD) tandem mass spectrometry is demonstrated for cyO8 as a method to address traditionally difficult-to-sequence cyclotide species. This work emphasizes the therapeutic and agricultural potential of natural product bioactive peptides and the necessity of developing robust analytical tools to deconvolute nature's complexity.
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Affiliation(s)
- Nicole C Parsley
- Department of Chemistry, University of North Carolina at Chapel Hill, NC, USA
| | | | | | | | - David W Hoskin
- Department of Pathology, Dalhousie University, Nova Scotia, Canada; Department of Microbiology and Immunology, Dalhousie University, Nova Scotia, Canada; Department of Surgery, Dalhousie University, Nova Scotia, Canada
| | | | - Leslie M Hicks
- Department of Chemistry, University of North Carolina at Chapel Hill, NC, USA.
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15
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Crittenden CM, Morrison LJ, Fitzpatrick MD, Myers AP, Novelli ET, Rosenberg J, Akin LD, Srinivasa S, Shear JB, Brodbelt JS. Towards mapping electrostatic interactions between Kdo 2-lipid A and cationic antimicrobial peptides via ultraviolet photodissociation mass spectrometry. Analyst 2018; 143:3607-3618. [PMID: 29968868 PMCID: PMC6056329 DOI: 10.1039/c8an00652k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Cationic antimicrobial peptides (CAMPs) have been known to act as multi-modal weapons against Gram-negative bacteria. As a new approach to investigate the nature of the interactions between CAMPs and the surfaces of bacteria, native mass spectrometry and two MS/MS strategies (ultraviolet photodissociation (UVPD) and higher energy collisional activation (HCD)) are used to examine formation and disassembly of saccharolipid·peptide complexes. Kdo2-lipid A (KLA) is used as a model saccharolipid to evaluate complexation with a series of cationic peptides (melittin and three analogs). Collisional activation of the KLA·peptide complexes results in the disruption of electrostatic interactions, resulting in apo-sequence ions with shifts in the distribution of ions compared to the fragmentation patterns of the apo-peptides. UVPD of the KLA·peptide complexes results in both apo- and holo-sequence ions of the peptides, the latter in which the KLA remains bound to the truncated peptide fragment despite cleavage of a covalent bond of the peptide backbone. Mapping both the N- and C-terminal holo-product ions gives insight into the peptide motifs (specifically an electropositive KRKR segment and a proline residue) that are responsible for mediating the electrostatic interactions between the cationic peptides and saccharolipid.
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Affiliation(s)
| | - Lindsay J Morrison
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA.
| | - Mignon D Fitzpatrick
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA.
| | - Allison P Myers
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA.
| | - Elisa T Novelli
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA.
| | - Jake Rosenberg
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA.
| | - Lucas D Akin
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA.
| | - Sorin Srinivasa
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA.
| | - Jason B Shear
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA.
| | - Jennifer S Brodbelt
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA.
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16
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Quick MM, Crittenden CM, Rosenberg JA, Brodbelt JS. Characterization of Disulfide Linkages in Proteins by 193 nm Ultraviolet Photodissociation (UVPD) Mass Spectrometry. Anal Chem 2018; 90:8523-8530. [PMID: 29902373 PMCID: PMC6050148 DOI: 10.1021/acs.analchem.8b01556] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Deciphering disulfide bond patterns in proteins remains a significant challenge. In the present study, interlinked disulfide bonds connecting peptide chains are homolytically cleaved with 193 nm ultraviolet photodissociation (UVPD). Analysis of insulin showcased the ability of UVPD to cleave multiple disulfide bonds and provide sequence coverage of the peptide chains in the same MS/MS event. For proteins containing more complex disulfide bonding patterns, an approach combining partial reduction and alkylation mitigated disulfide scrambling and allowed assignment of the array of disulfide bonds. The 4 disulfide bonds of lysozyme and the 19 disulfide bonds of serotransferrin were characterized through LC/UVPD-MS analysis of nonreduced and partially reduced protein digests.
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17
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Crittenden CM, Herrera CM, Williams PE, Ricci DP, Swem LR, Trent MS, Brodbelt JS. Mapping phosphate modifications of substituted lipid A via a targeted MS 3 CID/UVPD strategy. Analyst 2018; 143:3091-3099. [PMID: 29881855 PMCID: PMC6019210 DOI: 10.1039/c8an00561c] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Structural characterization of lipid A from Gram-negative bacteria remains a significant challenge, especially with respect to localizing modifications of the phosphate groups typically found on the reducing and non-reducing ends of the β-1',6-linked glucosamine disaccharide backbone of lipid A. As reported here, combining traditional collisional activated dissociation (CAD) and ultraviolet photodissociation (UVPD) in a hybrid MS3 approach facilitates identification and localization of substituents of the phosphate groups. The focus is on rapid identification and characterization of substituted lipid A species with specific emphasis on the modifications on the 1 and 4' phosphate moieties. Mapping these modifications, typically ones that modify the surface charges of lipopolysaccharides, is particularly important owing to the impact of these types of modifications on antibiotic resistance. The presence of phosphoethanolamine, aminoarabinose, and galactosamine moieties in hexaacylated and heptaacylated lipid A species, including ones from Enterobacter cloacae and Acinetobacter baumannii, are characterized using a targeted MS3 strategy to identify glycosidic product ions (1,5X1 and 0,4A2, typically) which allow localization of the substituents.
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18
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Crittenden CM, Akin LD, Morrison LJ, Trent MS, Brodbelt JS. Characterization of Lipid A Variants by Energy-Resolved Mass Spectrometry: Impact of Acyl Chains. J Am Soc Mass Spectrom 2017; 28:1118-1126. [PMID: 27966172 PMCID: PMC5438766 DOI: 10.1007/s13361-016-1542-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 10/19/2016] [Accepted: 10/24/2016] [Indexed: 05/04/2023]
Abstract
Lipid A molecules consist of a diglucosamine sugar core with a number of appended acyl chains that vary in their length and connectivity. Because of the challenging nature of characterizing these molecules and differentiating between isomeric species, an energy-resolved MS/MS strategy was undertaken to track the fragmentation trends and map genealogies of product ions originating from consecutive cleavages of acyl chains. Generalizations were developed based on the number and locations of the primary and secondary acyl chains as well as variations in preferential cleavages arising from the location of the phosphate groups. Secondary acyl chain cleavage occurs most readily for lipid A species at the 3' position, followed by primary acyl chain fragmentation at both the 3' and 3 positions. In the instances of bisphosphorylated lipid A variants, phosphate loss occurs readily in conjunction with the most favorable primary and secondary acyl chain cleavages. Graphical Abstract ᅟ.
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Affiliation(s)
| | - Lucas D Akin
- Department of Chemistry, University of Texas, Austin, TX, 78712, USA
| | | | - M Stephen Trent
- Department of Infectious Diseases, University of Georgia, Athens, GA, 30602, USA
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19
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Jenner ZB, Crittenden CM, Gonzalez M, Brodbelt JS, Bruns KA. Hydrocarbon-stapled lipopeptides exhibit selective antimicrobial activity. Biopolymers 2017; 108. [DOI: 10.1002/bip.23006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 11/22/2016] [Accepted: 11/27/2016] [Indexed: 12/27/2022]
Affiliation(s)
- Zachary B. Jenner
- Department of Chemistry and Biochemistry; Southwestern University; Georgetown Texas 78626
- Department of Microbiology; McGovern Medical School, formerly The University of Texas Health Science Center at Houston (UTHealth) Medical School; Texas 77030
| | | | - Martín Gonzalez
- Department of Biology; Southwestern University; Georgetown Texas 78626
| | | | - Kerry A. Bruns
- Department of Chemistry and Biochemistry; Southwestern University; Georgetown Texas 78626
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20
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Black DM, Crittenden CM, Brodbelt JS, Whetten RL. Ultraviolet Photodissociation of Selected Gold Clusters: Ultraefficient Unstapling and Ligand Stripping of Au 25(pMBA) 18 and Au 36(pMBA) 24. J Phys Chem Lett 2017; 8:1283-1289. [PMID: 28234006 DOI: 10.1021/acs.jpclett.7b00442] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
We report the first results of ultraviolet photodissociation (UVPD) mass spectrometry of trapped monolayer-protected cluster (MPC) ions generated by electrospray ionization. Gold clusters Au25(pMBA)18 and Au36(pMBA)24 (pMBA = para-mercaptobenzoic acid) were analyzed in both the positive and negative modes. Whereas activation methods including collisional- and electron-based methods produced relatively few fragment ions, even a single ultraviolet pulse (at λ = 193 nm) caused extensive fragmentation of the positively charged clusters. Upon photoactivation using a low number of laser pulses, the staple motifs of both clusters were cleaved and stripped of the protecting ligand portions without removal of any contained gold atoms. This striking process involved Au-S and C-S bond cleavages via a pathway made possible by 6.4 eV photon absorption. Monomer evaporation (neutral gold atom loss) occurred upon exposure to multiple pulses, resulting in a size series of bare gold-cluster ions. All tandem mass spectrometric methods produced the singly charged ring tetramer ion, [Au4(pMBA)4 + Na]+, for each cluster.
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Affiliation(s)
- David M Black
- Department of Physics and Astronomy, The University of Texas at San Antonio , San Antonio, Texas 78249, United States
| | | | - Jennifer S Brodbelt
- Department of Chemistry, The University of Texas at Austin , Austin, Texas 78712, United States
| | - Robert L Whetten
- Department of Physics and Astronomy, The University of Texas at San Antonio , San Antonio, Texas 78249, United States
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21
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Crittenden CM, Parker WR, Jenner ZB, Bruns KA, Akin LD, McGee WM, Ciccimaro E, Brodbelt JS. Exploitation of the Ornithine Effect Enhances Characterization of Stapled and Cyclic Peptides. J Am Soc Mass Spectrom 2016; 27:856-863. [PMID: 26864791 DOI: 10.1007/s13361-016-1355-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 01/13/2016] [Accepted: 01/22/2016] [Indexed: 06/05/2023]
Abstract
A method to facilitate the characterization of stapled or cyclic peptides is reported via an arginine-selective derivatization strategy coupled with MS/MS analysis. Arginine residues are converted to ornithine residues through a deguanidination reaction that installs a highly selectively cleavable site in peptides. Upon activation by CID or UVPD, the ornithine residue cyclizes to promote cleavage of the adjacent amide bond. This Arg-specific process offers a unique strategy for site-selective ring opening of stapled and cyclic peptides. Upon activation of each derivatized peptide, site-specific backbone cleavage at the ornithine residue results in two complementary products: the lactam ring-containing portion of the peptide and the amine-containing portion. The deguanidination process not only provides a specific marker site that initiates fragmentation of the peptide but also offers a means to unlock the staple and differentiate isobaric stapled peptides.
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Affiliation(s)
| | - W Ryan Parker
- Department of Chemistry, University of Texas, Austin, TX, 78712, USA
| | - Zachary B Jenner
- Department of Chemistry and Biochemistry, Southwestern University, Georgetown, TX, 78626, USA
| | - Kerry A Bruns
- Department of Chemistry and Biochemistry, Southwestern University, Georgetown, TX, 78626, USA
| | - Lucas D Akin
- Department of Chemistry, University of Texas, Austin, TX, 78712, USA
| | - William M McGee
- Department of Chemistry, University of Texas, Austin, TX, 78712, USA
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22
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Affiliation(s)
- J. Brett Kimbrell
- a Department of Chemistry , University of West Georgia , Carrollton , GA , 30118 , USA
| | - Joshua R. Hite
- a Department of Chemistry , University of West Georgia , Carrollton , GA , 30118 , USA
| | - Kristin N. Skala
- a Department of Chemistry , University of West Georgia , Carrollton , GA , 30118 , USA
| | | | | | - S. Swamy Mruthinti
- b Department of Biology , University of West Georgia , Carrollton , GA , 30118 , USA
| | - Megumi Fujita
- a Department of Chemistry , University of West Georgia , Carrollton , GA , 30118 , USA
| | - Farooq A. Khan
- a Department of Chemistry , University of West Georgia , Carrollton , GA , 30118 , USA
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