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Peker T, Zagiel B, Rocard L, Bich C, Sachon E, Moumné R. Analytical Tools for Dynamic Combinatorial Libraries of Cyclic Peptides. Chembiochem 2023; 24:e202300688. [PMID: 37815502 DOI: 10.1002/cbic.202300688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Accepted: 10/10/2023] [Indexed: 10/11/2023]
Abstract
Target-directed dynamic combinatorial chemistry is a very attractive strategy for the discovery of bioactive peptides. However, its application has not yet been demonstrated, presumably due to analytical challenges that arise from the diversity of a peptide library with combinatorial side-chains. We previously reported an efficient method to generate, under biocompatible conditions, large dynamic libraries of cyclic peptides grafted with amino acid's side-chains, by thiol-to-thioester exchanges. In this work, we present analytical tools to easily characterize such libraries by HPLC and mass spectrometry, and in particular to simplify the isomers' distinction requiring sequencing by MS/MS fragmentations. After structural optimization, the cyclic scaffold exhibits a UV-tag, absorbing at 415 nm, and an ornithine residue which favors the regioselective ring-opening and simultaneous MS/MS fragmentation, in the gas-phase.
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Affiliation(s)
- Taleen Peker
- Sorbonne Université, École Normale Supérieure, PSL University, CNRS, Laboratoire des Biomolécules, LBM, 75005, Paris, France
| | - Benjamin Zagiel
- Sorbonne Université, École Normale Supérieure, PSL University, CNRS, Laboratoire des Biomolécules, LBM, 75005, Paris, France
| | - Lou Rocard
- Sorbonne Université, École Normale Supérieure, PSL University, CNRS, Laboratoire des Biomolécules, LBM, 75005, Paris, France
| | - Claudia Bich
- UMR 5247-CNRS-UM-ENSCM, Institut des Biomolécules Max Mousseron (IBMM), Université de Montpellier, Montpellier, France
| | - Emmanuelle Sachon
- Sorbonne Université, École Normale Supérieure, PSL University, CNRS, Laboratoire des Biomolécules, LBM, 75005, Paris, France
- MS3U Platform, Fédération de Chimie Moléculaire de Paris Centre - FR2769, Sorbonne Université, 4 Place Jussieu, 75005, Paris, France
| | - Roba Moumné
- Sorbonne Université, École Normale Supérieure, PSL University, CNRS, Laboratoire des Biomolécules, LBM, 75005, Paris, France
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2
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Brodbelt JS, Morrison LJ, Santos I. Ultraviolet Photodissociation Mass Spectrometry for Analysis of Biological Molecules. Chem Rev 2020; 120:3328-3380. [PMID: 31851501 PMCID: PMC7145764 DOI: 10.1021/acs.chemrev.9b00440] [Citation(s) in RCA: 139] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The development of new ion-activation/dissociation methods continues to be one of the most active areas of mass spectrometry owing to the broad applications of tandem mass spectrometry in the identification and structural characterization of molecules. This Review will showcase the impact of ultraviolet photodissociation (UVPD) as a frontier strategy for generating informative fragmentation patterns of ions, especially for biological molecules whose complicated structures, subtle modifications, and large sizes often impede molecular characterization. UVPD energizes ions via absorption of high-energy photons, which allows access to new dissociation pathways relative to more conventional ion-activation methods. Applications of UVPD for the analysis of peptides, proteins, lipids, and other classes of biologically relevant molecules are emphasized in this Review.
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Affiliation(s)
- Jennifer S. Brodbelt
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Lindsay J. Morrison
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Inês Santos
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
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3
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Affiliation(s)
| | | | - Jennifer S. Brodbelt
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
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4
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Foreman DJ, Parsley NC, Lawler JT, Aryal UK, Hicks LM, McLuckey SA. Gas-Phase Sequencing of Cyclotides: Introduction of Selective Ring Opening at Dehydroalanine via Ion/Ion Reaction. Anal Chem 2019; 91:15608-15616. [PMID: 31746593 DOI: 10.1021/acs.analchem.9b03671] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The gas-phase linearization of cyclotides via site-selective ring opening at dehydroalanine residues and its application to cyclotide sequencing is presented. This strategy relies on the ability to incorporate dehydroalanine into macrocyclic peptide ions, which is easily accomplished through an ion/ion reaction. Triply protonated cyclotide cations are transformed into radical cations via ion/ion reaction with the sulfate radical anion. Subsequent activation of the cyclotide radical cation generates dehydroalanine at a single cysteine residue, which is easily identified by the odd-electron loss of ·SCH2CONH2. The presence of dehydroalanine in cyclotides provides a site-selective ring-opening pathway that, in turn, generates linear cyclotide analogues in the gas phase. Unlike cyclic variants, product ions derived from the linear peptides provide rich sequence information. The sequencing capability of this strategy is demonstrated with four known cyclotides found in Viola inconspicua, where, in each case, greater than 93% sequence coverage was observed. Furthermore, the utility of this method is highlighted by the partial de novo sequencing of an unknown cyclotide with much greater sequence coverage than that obtained with a conventional Glu-C digestion approach. This method is particularly well-suited for cyclotide species that are not abundant enough to characterize with traditional methods.
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Affiliation(s)
| | - Nicole C Parsley
- Department of Chemistry , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27514 , United States
| | | | | | - Leslie M Hicks
- Department of Chemistry , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27514 , United States
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Marshall SR, Stoudt ML, DiVittorio MA, Sargent AL, Allen WE. Side-Chain Protonation States of a Fluorescent Arginine. J Org Chem 2019; 84:14407-14413. [PMID: 31608637 DOI: 10.1021/acs.joc.9b00677] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An arginine derivative with a fluorescent side-chain, Boc-Arg(Nap)-OH, was prepared by palladium(0)-catalyzed coupling of Boc-Arg-OH with a 4-bromonaphthalimide. The presence of the fluorophore lowers the pKa of the side-chain guanidinium group by several orders of magnitude, to 9.0 (±0.1), allowing the derivative to access an electrically neutral protonation state that is not generally available to arginine itself. Computational modeling (DFT) predicts that protonation takes place at the side-chain C═N atom that bears the fluorophore. Calculated electronic absorptions for the protonated (356 nm) and neutral species (440 nm) are in good agreement with experiment. When irradiated with light, excited-state proton transfer (ESPT) occurs from cationic side-chains to suitably basic solvents, resulting in fluorescence emission from the neutral species. Arg(Nap) can be incorporated into peptides with sterically accessible N-termini using specially adapted conditions of solid-phase peptide synthesis.
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Affiliation(s)
- Sarah R Marshall
- Department of Chemistry, Science and Technology Building , East Carolina University , Greenville , North Carolina 27858-4353 , United States
| | - Mikayla L Stoudt
- Department of Chemistry, Science and Technology Building , East Carolina University , Greenville , North Carolina 27858-4353 , United States
| | - Madeleine A DiVittorio
- Department of Chemistry, Science and Technology Building , East Carolina University , Greenville , North Carolina 27858-4353 , United States
| | - Andrew L Sargent
- Department of Chemistry, Science and Technology Building , East Carolina University , Greenville , North Carolina 27858-4353 , United States
| | - William E Allen
- Department of Chemistry, Science and Technology Building , East Carolina University , Greenville , North Carolina 27858-4353 , United States
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6
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Foreman DJ, Lawler JT, Niedrauer ML, Hostetler MA, McLuckey SA. Gold(I) Cationization Promotes Ring Opening in Lysine-Containing Cyclic Peptides. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2019; 30:1914-1922. [PMID: 31250319 PMCID: PMC6812625 DOI: 10.1007/s13361-019-02247-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 05/07/2019] [Accepted: 05/07/2019] [Indexed: 06/09/2023]
Abstract
A strategy to sequence lysine-containing cyclic peptides by MSn is presented. Doubly protonated cyclic peptides ions are transformed into gold (I) cationized peptide ions via cation switching ion/ion reaction. Gold(I) cationization facilitates the oxidation of neutral lysine residues in the gas phase, weakening the adjacent amide bond. Upon activation, facile cleavage N-terminal to the oxidized lysine residue provides a site-specific ring opening pathway that converts cyclic peptides into acyclic analogs. The ensuing ion contains a cyclic imine as the new N-terminus and an oxazolone, or structural equivalent, as the new C-terminus. Product ions are formed from subsequent fragmentation events of the linearized peptide ion. Such an approach simplifies MS/MS data interpretation as a series of fragment ions with common N- and C-termini are generated. Results are presented for two cyclic peptides, sunflower trypsin inhibitor and the model cyclic peptide, β-Loop. The power of this strategy lies in the ability to generate the oxidized peptide, which is easily identified via the loss of HAuNH3 from [M + Au]+. While some competitive processes are observed, the site of ring opening can be pinpointed to the lysine residue upon MS4 enabling the unambiguous sequencing of cyclic peptides.
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Affiliation(s)
- David J Foreman
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47907-2084, USA
| | - John T Lawler
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47907-2084, USA
| | - Mary L Niedrauer
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47907-2084, USA
| | - Matthew A Hostetler
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47907-2084, USA
| | - Scott A McLuckey
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47907-2084, USA.
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Smith ZM, Wang X, Scheerer JR, Martens J, Berden G, Oomens J, Steinmetz V, Somogyi A, Wysocki V, Poutsma JC. Spectroscopic Evidence for Lactam Formation in Terminal Ornithine b 2+ and b 3+ Fragment Ions. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2019; 30:1565-1577. [PMID: 31183839 PMCID: PMC6697629 DOI: 10.1007/s13361-019-02244-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 04/24/2019] [Accepted: 04/26/2019] [Indexed: 06/09/2023]
Abstract
Infrared multiple photon dissociation action spectroscopy was performed on the AlaOrn b2+ and AlaAlaOrn b3+ fragment ions from ornithine-containing tetrapeptides. Infrared spectra were obtained in the fingerprint region (1000-2000 cm-1) using the infrared free electron lasers at the Centre Laser Infrarouge d'Orsay (CLIO) facility in Orsay, France, and the free electron lasers for infrared experiments (FELIX) facility in Nijmegen, the Netherlands. A novel terminal ornithine lactam AO+ b2+ structure was synthesized for experimental comparison and spectroscopy confirms that the b2+ fragment ion from AOAA forms a lactam structure. Comparison of experimental spectra with scaled harmonic frequencies at the B3LYP/6-31+G(d,p) level of theory shows that AO+ b2+ forms a terminal lactam protonated either on the lactam carbonyl oxygen or the N-terminal nitrogen atom. Several low-lying conformers of these isomers are likely populated following IRMPD dissociation. Similarly, a comparison of the experimental IRMPD spectrum with calculated spectra shows that AAO+ b3+-ions also adopt a lactam structure, again with multiple different protonation sites, during fragmentation. This study provides spectroscopic confirmation for the lactam cyclization proposed for the "ornithine effect" and represents an alternative bn+ structure to the oxazolone and diketopiperazine/macrocycle structures most often formed.
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Affiliation(s)
- Zachary M Smith
- Department of Chemistry, The College of William & Mary, Williamsburg, VA, 23187-8795, USA
| | - Xiye Wang
- Department of Chemistry, The College of William & Mary, Williamsburg, VA, 23187-8795, USA
| | - Jonathan R Scheerer
- Department of Chemistry, The College of William & Mary, Williamsburg, VA, 23187-8795, USA
| | - Jonathan Martens
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Nijmegen, The Netherlands
| | - Giel Berden
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Nijmegen, The Netherlands
| | - Jos Oomens
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Nijmegen, The Netherlands
| | - Vincent Steinmetz
- Laboratorie de Chimie Physique, CNRS UMR 8000, Université Paris, 91405, Orsay, France
| | - Arpad Somogyi
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210-1173, USA
| | - Vicki Wysocki
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210-1173, USA
| | - John C Poutsma
- Department of Chemistry, The College of William & Mary, Williamsburg, VA, 23187-8795, USA.
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Attard TJ, Carter MD, Fang M, Johnson RC, Reid GE. Structural Characterization and Absolute Quantification of Microcystin Peptides Using Collision-Induced and Ultraviolet Photo-Dissociation Tandem Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2018; 29:1812-1825. [PMID: 29845563 PMCID: PMC6088756 DOI: 10.1007/s13361-018-1981-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 04/21/2018] [Accepted: 04/25/2018] [Indexed: 05/23/2023]
Abstract
Microcystin (MC) peptides produced by cyanobacteria pose a hepatotoxic threat to human health upon ingestion from contaminated drinking water. While rapid MC identification and quantification in contaminated body fluids or tissue samples is important for patient treatment and outcomes, conventional immunoassay-based measurement strategies typically lack the specificity required for unambiguous determination of specific MC variants, whose toxicity can significantly vary depending on their structures. Furthermore, the unambiguous identification and accurate quantitation of MC variants using tandem mass spectrometry (MS/MS)-based methods can be limited due to a current lack of appropriate stable isotope-labeled internal standards. To address these limitations, we have systematically examined here the sequence and charge state dependence to the formation and absolute abundance of both "global" and "variant-specific" product ions from representative MC-LR, MC-YR, MC-RR, and MC-LA peptides, using higher-energy collisional dissociation (HCD)-MS/MS, ion-trap collision-induced dissociation (CID)-MS/MS and CID-MS3, and 193 nm ultraviolet photodissociation (UPVD)-MS/MS. HCD-MS/MS was found to provide the greatest detection sensitivity for both global and variant-specific product ions in each of the MC variants, except for MC-YR where a variant-specific product uniquely formed via UPVD-MS/MS was observed with the greatest absolute abundance. A simple methodology for the preparation and characterization of 18O-stable isotope-labeled MC reference materials for use as internal standards was also developed. Finally, we have demonstrated the applicability of the methods developed herein for absolute quantification of MC-LR present in human urine samples, using capillary scale liquid chromatography coupled with ultra-high resolution / accurate mass spectrometry and HCD-MS/MS. Graphical abstract ᅟ.
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Affiliation(s)
- Troy J Attard
- School of Chemistry, The University of Melbourne, Melbourne, VIC, Australia
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC, Australia
| | - Melissa D Carter
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Mengxuan Fang
- School of Chemistry, The University of Melbourne, Melbourne, VIC, Australia
| | - Rudolph C Johnson
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Gavin E Reid
- School of Chemistry, The University of Melbourne, Melbourne, VIC, Australia.
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC, Australia.
- Department of Biochemistry and Molecular Biology, The University of Melbourne, Melbourne, VIC, Australia.
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9
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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: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [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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Rautenbach M, Vlok NM, Eyéghé-Bickong HA, van der Merwe MJ, Stander MA. An Electrospray Ionization Mass Spectrometry Study on the "In Vacuo" Hetero-Oligomers Formed by the Antimicrobial Peptides, Surfactin and Gramicidin S. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:1623-1637. [PMID: 28560564 DOI: 10.1007/s13361-017-1685-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 04/08/2017] [Accepted: 04/11/2017] [Indexed: 06/07/2023]
Abstract
It was previously observed that the lipopeptide surfactants in surfactin (Srf) have an antagonistic action towards the highly potent antimicrobial cyclodecapeptide, gramicidin S (GS). This study reports on some of the molecular aspects of the antagonism as investigated through complementary electrospray ionization mass spectrometry techniques. We were able to detect stable 1:1 and 2:1 hetero-oligomers in a mixture of surfactin and gramicidin S. The noncovalent interaction between GS and Srf, with the proposed equilibrium: GS~Srf↔GS+Srf correlated to apparent K d values of 6-9 μM in gas-phase and 1 μM in aqueous solution. The apparent K d values decreased with a longer incubation time and indicated a slow oligomerization equilibrium. Furthermore, the low μM K dapp values of GS~Srf↔GS+Srf fell within the biological concentration range and related to the 2- to 3-fold increase in [GS] needed for bacterial growth inhibition in the presence of Srf. Competition studies indicated that neither Na+ nor Ca2+ had a major effect on the stability of preformed heterodimers and that GS in fact out-competed Ca2+ and Na+ from Srf. Traveling wave ion mobility mass spectrometry revealed near symmetrical peaks of the heterodimers correlating to a compact dimer conformation that depend on specific interactions. Collision-induced dissociation studies indicated that the peptide interaction is most probably between one Orn residue in GS and the Asp residue, but not the Glu residue in Srf. We propose that flanking hydrophobic residues in both peptides stabilize the antagonistic and inactive peptide hetero-oligomers and shield the specific polar interactions in an aqueous environment. Graphical Abstract ᅟ.
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Affiliation(s)
- Marina Rautenbach
- BIOPEP® Peptide Group, University of Stellenbosch, Stellenbosch, 7602, Republic of South Africa.
- Department of Biochemistry, University of Stellenbosch, Stellenbosch, 7602, Republic of South Africa.
| | - N Maré Vlok
- BIOPEP® Peptide Group, University of Stellenbosch, Stellenbosch, 7602, Republic of South Africa
- Department of Biochemistry, University of Stellenbosch, Stellenbosch, 7602, Republic of South Africa
| | - Hans A Eyéghé-Bickong
- BIOPEP® Peptide Group, University of Stellenbosch, Stellenbosch, 7602, Republic of South Africa
- Department of Biochemistry, University of Stellenbosch, Stellenbosch, 7602, Republic of South Africa
| | - Marthinus J van der Merwe
- Department of Biochemistry, University of Stellenbosch, Stellenbosch, 7602, Republic of South Africa
- LCMS Central Analytical Facility, University of Stellenbosch, Stellenbosch, 7602, Republic of South Africa
| | - Marietjie A Stander
- Department of Biochemistry, University of Stellenbosch, Stellenbosch, 7602, Republic of South Africa
- LCMS Central Analytical Facility, University of Stellenbosch, Stellenbosch, 7602, Republic of South Africa
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