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Vasileva ID, Samgina TY, Meng Z, Zubarev RA, Lebedev AT. EThcD Benefits for the Sequencing Inside Intramolecular Disulfide Cycles of Amphibian Intact Peptides. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2023; 34:1979-1988. [PMID: 37525119 DOI: 10.1021/jasms.3c00127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/02/2023]
Abstract
Disulfide bonds formed by a pair of cysteine residues in the peptides' backbone represent a certain problem for their sequencing by means of mass spectrometry. As a rule, in proteomics, disulfide bonds should be cleaved before the analysis followed by some sort of chemical derivatization. That step is time-consuming and may lead to losses of minor peptides of the analyzed mixtures due to incomplete reaction, adsorption on the walls of the vials, etc. Certain problems in the de novo top-down sequencing of amphibian skin peptides are caused by the C-terminal disulfide loop, called the Rana box. Its reduction with or without subsequent derivatization was considered to be an unavoidable step before mass spectrometry. In the present study, EThcD demonstrated its efficiency in sequencing intact disulfide-containing peptides without any preliminary derivatization. Applied to the secretion of three frog species, EThcD provided the full sequence inside the intramolecular disulfide cycle for all S-S-containing peptides found in the samples, with the only exception being diarginine species. Proteolytic fragments, which are shorter than the original peptides, were helpful in some cases. HCD should be mentioned as a complementary tool to the EThcD tool, being useful as a confirmation method for some sequence details.
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Affiliation(s)
- Irina D Vasileva
- Lomonosov Moscow State University, Department of Organic Chemistry, 119991 Moscow, Russia
| | - Tatiana Yu Samgina
- Lomonosov Moscow State University, Department of Organic Chemistry, 119991 Moscow, Russia
| | - Zhaowei Meng
- Department of Medicinal Biochemistry and Biophysics, Division of Molecular Biometry, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Roman A Zubarev
- Department of Medicinal Biochemistry and Biophysics, Division of Molecular Biometry, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Albert T Lebedev
- Lomonosov Moscow State University, Department of Organic Chemistry, 119991 Moscow, Russia
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2
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Ng CCA, Zhou Y, Yao ZP. Algorithms for de-novo sequencing of peptides by tandem mass spectrometry: A review. Anal Chim Acta 2023; 1268:341330. [PMID: 37268337 DOI: 10.1016/j.aca.2023.341330] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 05/04/2023] [Accepted: 05/06/2023] [Indexed: 06/04/2023]
Abstract
Peptide sequencing is of great significance to fundamental and applied research in the fields such as chemical, biological, medicinal and pharmaceutical sciences. With the rapid development of mass spectrometry and sequencing algorithms, de-novo peptide sequencing using tandem mass spectrometry (MS/MS) has become the main method for determining amino acid sequences of novel and unknown peptides. Advanced algorithms allow the amino acid sequence information to be accurately obtained from MS/MS spectra in short time. In this review, algorithms from exhaustive search to the state-of-art machine learning and neural network for high-throughput and automated de-novo sequencing are introduced and compared. Impacts of datasets on algorithm performance are highlighted. The current limitations and promising direction of de-novo peptide sequencing are also discussed in this review.
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Affiliation(s)
- Cheuk Chi A Ng
- State Key Laboratory of Chemical Biology and Drug Discovery, and Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Special Administrative Region of China; Research Institute for Future Food, and Research Center for Chinese Medicine Innovation, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Special Administrative Region of China; State Key Laboratory of Chinese Medicine and Molecular Pharmacology (Incubation), and Shenzhen Key Laboratory of Food Biological Safety Control, The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, 518057, China
| | - Yin Zhou
- State Key Laboratory of Chemical Biology and Drug Discovery, and Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Special Administrative Region of China; Research Institute for Future Food, and Research Center for Chinese Medicine Innovation, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Special Administrative Region of China; State Key Laboratory of Chinese Medicine and Molecular Pharmacology (Incubation), and Shenzhen Key Laboratory of Food Biological Safety Control, The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, 518057, China
| | - Zhong-Ping Yao
- State Key Laboratory of Chemical Biology and Drug Discovery, and Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Special Administrative Region of China; Research Institute for Future Food, and Research Center for Chinese Medicine Innovation, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Special Administrative Region of China; State Key Laboratory of Chinese Medicine and Molecular Pharmacology (Incubation), and Shenzhen Key Laboratory of Food Biological Safety Control, The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, 518057, China.
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3
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Lebedev AT, Vasileva ID, Samgina TY. FT-MS in the de novo top-down sequencing of natural nontryptic peptides. MASS SPECTROMETRY REVIEWS 2022; 41:284-313. [PMID: 33347655 DOI: 10.1002/mas.21678] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 11/25/2020] [Accepted: 11/25/2020] [Indexed: 06/12/2023]
Abstract
The present review covers available results on the application of FT-MS for the de novo sequencing of natural peptides of various animals: cones, bees, snakes, amphibians, scorpions, and so forth. As these peptides are usually bioactive, the animals efficiently use them as a weapon against microorganisms or higher animals including predators. These peptides represent definite interest as drugs of future generations since the mechanism of their activity is completely different in comparison with that of the modern antibiotics. Utilization of those peptides as antibiotics can eliminate the problem of the bacterial resistance development. Sequence elucidation of these bioactive peptides becomes even more challenging when the species genome is not available and little is known about the protein origin and other properties of those peptides in the study. De novo sequencing may be the only option to obtain sequence information. The benefits of FT-MS for the top-down peptide sequencing, the general approaches of the de novxxo sequencing, the difficult cases involving sequence coverage, isobaric and isomeric amino acids, cyclization of short peptides, the presence of posttranslational modifications will be discussed in the review.
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Affiliation(s)
- Albert T Lebedev
- Organic Chemistry Department, M.V. Lomonosov Moscow State University, Moscow, Russia
| | - Irina D Vasileva
- Organic Chemistry Department, M.V. Lomonosov Moscow State University, Moscow, Russia
| | - Tatiana Y Samgina
- Organic Chemistry Department, M.V. Lomonosov Moscow State University, Moscow, Russia
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4
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Logerot E, Enjalbal C. Dissociation Pattern of Sodiated Amide Peptides as a Tool for De Novo Sequencing. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:2328-2337. [PMID: 33064467 DOI: 10.1021/jasms.0c00269] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
As part of the de novo sequencing issue, new approaches have to be found to sequence small natural peptides (<15-20 residues), which often present amino acid compositions, inducing merely singly charged species, that are quite difficult to thoroughly fragment under low-energy activation conditions in MS/MS experiments. Cationization by alkali metals, like Na+, followed by collision-induced dissociations (CID) or the postsource metastable decay (PSD) of such cationized molecular ions was found to improve the sequence coverage of native peptides through the formation of [bn-1 + Na + OH]+ ions issued from C-terminal residue exclusion. Concerned by the identification of peptides with a C-terminal amide, the fragmentation pattern of their sodiated molecular ions was investigated. In contrast to the peptides featuring unmodified C-termini, the C-terminal loss did not occur, with the amide function triggering different fragmentation pathways. However, several residues, such as aspartic acid (D), glutamic acid (E), and arginine (R), influenced the dissociation of fixed-charge sodiated ions similarly to protonated peptides; more surprisingly, serine (S), threonine (T), and tyrosine (Y), which exhibit a hydroxyl function on their side chains, showed a very peculiar behavior that could help de novo peptide sequencing.
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Affiliation(s)
- Elodie Logerot
- IBMM, CNRS, ENSCM, University of Montpellier, 34095 Montpellier, France
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5
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Valli M, Russo HM, Pilon AC, Pinto MEF, Dias NB, Freire RT, Castro-Gamboa I, Bolzani VDS. Computational methods for NMR and MS for structure elucidation I: software for basic NMR. PHYSICAL SCIENCES REVIEWS 2019. [DOI: 10.1515/psr-2018-0108] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Abstract
Structure elucidation is an important and sometimes time-consuming step for natural products research. This step has evolved in the past few years to a faster and more automated process due to the development of several computational programs and analytical techniques. In this paper, the topics of NMR prediction and CASE programs are addressed. Furthermore, the elucidation of natural peptides is discussed.
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6
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Wang B, Liu J, Cao J, Wang H, Guan X, Wei Z, Guo X. Investigation of c ions formed by N-terminally charged peptides upon collision-induced dissociation. JOURNAL OF MASS SPECTROMETRY : JMS 2016; 51:989-997. [PMID: 27537939 DOI: 10.1002/jms.3841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 08/16/2016] [Indexed: 06/06/2023]
Abstract
Peptide fragments such as b and y sequence ions generated upon low-energy collision-induced dissociation have been routinely used for tandem mass spectrometry (MS/MS)-based peptide/protein identification. The underlying formation mechanisms have been studied extensively and described within the literature. As a result, the 'mobile proton model' and 'pathways in competition model' have been built to interpret a majority of peptide fragmentation behavior. However, unusual peptide fragments which involve unfamiliar fragmentation pathways or various rearrangement reactions occasionally appear in MS/MS spectra, resulting in confused MS/MS interpretations. In this work, a series of unfamiliar c ions are detected in MS/MS spectra of the model peptides having an N-terminal Arg or deuterohemin group upon low-energy collision-induced dissociation process. Both the protonated Arg and deuterohemin group play an important role in retention of a positive charge at the N-terminus that is remote from the cleavage sites. According to previous reports and our studies involving amino acid substitutions and hydrogen-deuterium exchange, we propose a McLafferty-type rearrangement via charge-remote fragmentation as the potential mechanism to explain the formation of c ions from precursor peptide ions or unconventional b ions. Density functional theory calculations are also employed in order to elucidate the proposed fragmentation mechanisms. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Bing Wang
- College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun, 130012, China
| | - Jinrong Liu
- College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun, 130012, China
| | - Jungang Cao
- College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun, 130012, China
| | - Huixin Wang
- College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun, 130012, China
| | - Xinshu Guan
- College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun, 130012, China
| | - Zhonglin Wei
- College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun, 130012, China
| | - Xinhua Guo
- College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun, 130012, China.
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7
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Pilo AL, Peng Z, McLuckey SA. The dehydroalanine effect in the fragmentation of ions derived from polypeptides. JOURNAL OF MASS SPECTROMETRY : JMS 2016; 51:857-866. [PMID: 27484024 PMCID: PMC5068825 DOI: 10.1002/jms.3831] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 07/27/2016] [Accepted: 07/28/2016] [Indexed: 05/11/2023]
Abstract
The fragmentation of peptides and proteins upon collision-induced dissociation (CID) is highly dependent on sequence and ion type (e.g. protonated, deprotonated, sodiated, odd electron, etc.). Some amino acids, for example aspartic acid and proline, have been found to enhance certain cleavages along the backbone. Here, we show that peptides and proteins containing dehydroalanine, a non-proteinogenic amino acid with an unsaturated side-chain, undergo enhanced cleavage of the N-Cα bond of the dehydroalanine residue to generate c- and z-ions. Because these fragment ion types are not commonly observed upon activation of positively charged even-electron species, they can be used to identify dehydroalanine residues and localize them within the peptide or protein chain. While dehydroalanine can be generated in solution, it can also be generated in the gas phase upon CID of various species. Oxidized S-alkyl cysteine residues generate dehydroalanine upon activation via highly efficient loss of the alkyl sulfenic acid. Asymmetric cleavage of disulfide bonds upon collisional activation of systems with limited proton mobility also generates dehydroalanine. Furthermore, we show that gas-phase ion/ion reactions can be used to facilitate the generation of dehydroalanine residues via, for example, oxidation of S-alkyl cysteine residues and conversion of multiply-protonated peptides to radical cations. In the latter case, loss of radical side-chains to generate dehydroalanine from some amino acids gives rise to the possibility for residue-specific backbone cleavage of polypeptide ions. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Alice L Pilo
- Department of Chemistry, Purdue University, West Lafayette, IN, 47907-2084, USA
| | - Zhou Peng
- Department of Chemistry, Purdue University, West Lafayette, IN, 47907-2084, USA
| | - Scott A McLuckey
- Department of Chemistry, Purdue University, West Lafayette, IN, 47907-2084, USA.
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8
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Medzihradszky KF, Chalkley RJ. Lessons in de novo peptide sequencing by tandem mass spectrometry. MASS SPECTROMETRY REVIEWS 2015; 34:43-63. [PMID: 25667941 PMCID: PMC4367481 DOI: 10.1002/mas.21406] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Mass spectrometry has become the method of choice for the qualitative and quantitative characterization of protein mixtures isolated from all kinds of living organisms. The raw data in these studies are MS/MS spectra, usually of peptides produced by proteolytic digestion of a protein. These spectra are "translated" into peptide sequences, normally with the help of various search engines. Data acquisition and interpretation have both been automated, and most researchers look only at the summary of the identifications without ever viewing the underlying raw data used for assignments. Automated analysis of data is essential due to the volume produced. However, being familiar with the finer intricacies of peptide fragmentation processes, and experiencing the difficulties of manual data interpretation allow a researcher to be able to more critically evaluate key results, particularly because there are many known rules of peptide fragmentation that are not incorporated into search engine scoring. Since the most commonly used MS/MS activation method is collision-induced dissociation (CID), in this article we present a brief review of the history of peptide CID analysis. Next, we provide a detailed tutorial on how to determine peptide sequences from CID data. Although the focus of the tutorial is de novo sequencing, the lessons learned and resources supplied are useful for data interpretation in general.
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9
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Borges CR, Sherma ND. Techniques for the analysis of cysteine sulfhydryls and oxidative protein folding. Antioxid Redox Signal 2014; 21:511-31. [PMID: 24383618 PMCID: PMC4076987 DOI: 10.1089/ars.2013.5559] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
SIGNIFICANCE Modification of cysteine thiols dramatically affects protein function and stability. Hence, the abilities to quantify specific protein sulfhydryl groups within complex biological samples and map disulfide bond structures are crucial to gaining greater insights into how proteins operate in human health and disease. RECENT ADVANCES Many different molecular probes are now commercially available to label and track cysteine residues at great sensitivity. Coupled with mass spectrometry, stable isotope-labeled sulfhydryl-specific reagents can provide previously unprecedented molecular insights into the dynamics of cysteine modification. Likewise, the combined application of modern mass spectrometers with improved sample preparation techniques and novel data mining algorithms is beginning to routinize the analysis of complex protein disulfide structures. CRITICAL ISSUES Proper application of these modern tools and techniques, however, still requires fundamental understanding of sulfhydryl chemistry as well as the assumptions that accompany sample preparation and underlie effective data interpretation. FUTURE DIRECTIONS The continued development of tools, technical approaches, and corresponding data processing algorithms will, undoubtedly, facilitate site-specific protein sulfhydryl quantification and disulfide structure analysis from within complex biological mixtures with ever-improving accuracy and sensitivity. Fully routinizing disulfide structure analysis will require an equal but balanced focus on sample preparation and corresponding mass spectral dataset reproducibility.
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Affiliation(s)
- Chad R Borges
- Center for Personalized Diagnostics, The Biodesign Institute at Arizona State University , Tempe, Arizona
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10
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Goyder MS, Rebeaud F, Pfeifer ME, Kálmán F. Strategies in mass spectrometry for the assignment of Cys-Cys disulfide connectivities in proteins. Expert Rev Proteomics 2013; 10:489-501. [PMID: 24087910 DOI: 10.1586/14789450.2013.837663] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Elucidating disulfide linkage patterns is a crucial part of protein characterization, for which mass spectrometry (MS) is now an indispensable analytical tool. In many cases, MS-based disulfide connectivity assignment is straightforwardly achieved using one-step protein fragmentation in the unreduced form followed by mass measurement of bridged fragments. By contrast, venom proteins, which are receiving increasing interest as potential therapeutics, are a challenge for MS-based disulfide assignment due to their numerous closely spaced cysteines and knotted disulfide structure, requiring creative strategies to determine their connectivity. Today, these include the use of an array of reagents for enzymatic and/or chemical cleavage, partial reduction, differential cysteine labeling and tandem MS. This review aims to describe the toolkit of techniques available to MS users approaching both straightforward and complex disulfide bridge assignments, with a particular focus on strategies utilizing standard instrumentation found in a well-equipped analytical or proteomics laboratory.
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Affiliation(s)
- Miriam S Goyder
- Institute of Life Technologies, University of Applied Sciences Western Switzerland (HES-SO Valais/Wallis), 1950 Sion, Switzerland
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11
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Ogawa N, Taylor RM, Woodbury DJ, Prince JT. Resolving double disulfide bond patterns in SNAP25B using liquid chromatography-ion trap mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2013; 48:660-668. [PMID: 23722956 DOI: 10.1002/jms.3211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 03/26/2013] [Accepted: 03/27/2013] [Indexed: 06/02/2023]
Abstract
Complex disulfide bond patterns in synaptosomal-associated protein of 25 kD B (SNAP25B) are thought to regulate neurotransmitter release in response to oxidative stress. However, the steric feasibility of each possible disulfide pattern in SNAP25B has not been assessed. To assess the steric feasibility of hypothesized closely spaced complex disulfide patterning in SNAP25B and also the feasibility of identifying complex disulfide bond patterns with MS, we have developed a novel probabilistic analysis to unambiguously resolve complex double disulfide bond patterns by using an ion trap mass spectrometer. We analyzed fragmentation patterns of singly linked peptides to determine likely fragmentation events in an ion trap mass spectrometer and observed double and single backbone cleavage along with heterolytic cleavage of the disulfide bond. We modeled these same events in the doubly disulfide linked SNAP25B peptide and used a cumulative hypergeometric distribution with top-down scoring to both identify and differentiate these bonding patterns. Because of the presence of unique MS/MS peaks, two of the bonding patterns were directly identified. The third was assigned on the basis of full chromatographic separation and confirmed by modeling triple breakage fragments. In total, this work demonstrates the feasibility--and also limitations--of identification of complex intradisulfide patterns by using ion trap-based collision-induced dissociation-based fragmentation methods.
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Affiliation(s)
- Nozomi Ogawa
- Brigham Young University, Neuroscience Center and Department of Physiology and Developmental Biology, Provo, UT, USA
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Guthals A, Clauser KR, Frank AM, Bandeira N. Sequencing-grade de novo analysis of MS/MS triplets (CID/HCD/ETD) from overlapping peptides. J Proteome Res 2013; 12:2846-57. [PMID: 23679345 DOI: 10.1021/pr400173d] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Full-length de novo sequencing of unknown proteins remains a challenging open problem. Traditional methods that sequence spectra individually are limited by short peptide length, incomplete peptide fragmentation, and ambiguous de novo interpretations. We address these issues by determining consensus sequences for assembled tandem mass (MS/MS) spectra from overlapping peptides (e.g., by using multiple enzymatic digests). We have combined electron-transfer dissociation (ETD) with collision-induced dissociation (CID) and higher-energy collision-induced dissociation (HCD) fragmentation methods to boost interpretation of long, highly charged peptides and take advantage of corroborating b/y/c/z ions in CID/HCD/ETD. Using these strategies, we show that triplet CID/HCD/ETD MS/MS spectra from overlapping peptides yield de novo sequences of average length 70 AA and as long as 200 AA at up to 99% sequencing accuracy.
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Affiliation(s)
- Adrian Guthals
- Department of Computer Science and Engineering, University of California San Diego, La Jolla, California 92093, United States
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Guthals A, Bandeira N. Peptide identification by tandem mass spectrometry with alternate fragmentation modes. Mol Cell Proteomics 2012; 11:550-7. [PMID: 22595789 PMCID: PMC3434779 DOI: 10.1074/mcp.r112.018556] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 05/04/2012] [Indexed: 11/06/2022] Open
Abstract
The high-throughput nature of proteomics mass spectrometry is enabled by a productive combination of data acquisition protocols and the computational tools used to interpret the resulting spectra. One of the key components in mainstream protocols is the generation of tandem mass (MS/MS) spectra by peptide fragmentation using collision induced dissociation, the approach currently used in the large majority of proteomics experiments to routinely identify hundreds to thousands of proteins from single mass spectrometry runs. Complementary to these, alternative peptide fragmentation methods such as electron capture/transfer dissociation and higher-energy collision dissociation have consistently achieved significant improvements in the identification of certain classes of peptides, proteins, and post-translational modifications. Recognizing these advantages, mass spectrometry instruments now conveniently support fine-tuned methods that automatically alternate between peptide fragmentation modes for either different types of peptides or for acquisition of multiple MS/MS spectra from each peptide. But although these developments have the potential to substantially improve peptide identification, their routine application requires corresponding adjustments to the software tools and procedures used for automated downstream processing. This review discusses the computational implications of alternative and alternate modes of MS/MS peptide fragmentation and addresses some practical aspects of using such protocols for identification of peptides and post-translational modifications.
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Affiliation(s)
- Adrian Guthals
- Department of Computer Science and Engineering, University of California, San Diego, California, USA
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Sokolowska I, Ngounou Wetie AG, Woods AG, Darie CC. Automatic determination of disulfide bridges in proteins. ACTA ACUST UNITED AC 2012; 17:408-16. [PMID: 22885790 DOI: 10.1177/2211068212454737] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Precise determination of disulfide linkages between cysteine (Cys) residues in proteins is essential in the determination of protein structure. Therefore, a reliable automated method for the identification of disulfide bridges can serve as an important tool in the analysis of the tertiary structure of proteins of interest. Here, we describe the current and past methods used to identify disulfide bridges in proteins, with a focus on mass spectrometry (MS)-based methods and a particular emphasis on nanoliquid chromatography-tandem mass spectrometry (nanoLC-MS/MS)-based methods. We also show the development of an easy method based on the separation of disulfide-linked proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under denaturing and nonreducing conditions and selective in-gel digestion of proteins using reducing and nonreducing conditions, followed by analysis of the resulting peptide mixture by nanoACQUITY UPLC coupled to a quadrupole time-of-flight (QTOF) Micro mass spectrometer (nanoLC-MS/MS). Data-dependent analysis (DDA) nanoLC-MS/MS and information-dependent analysis (IDA) nanoLC-MS/MS were used for random and targeted identification of disulfide-linked peptides. Finally, an example of electrospray-MS (ESI-MS) and ESI-MS/MS-based determination of disulfide-linked peptides is shown.
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