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Novel C(β)–C(γ) Bond Cleavages of Tryptophan-Containing Peptide Radical Cations
In this study, we observed unprecedented cleavages of the C(β)–C(γ) bonds of tryptophan residue side chains in a series of hydrogen-deficient tryptophan-containing peptide radical cations (M(•+)) during low-energy collision-induced dissociation (CID). We used CID experiments and theoretical density...
Autores principales: | , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Springer-Verlag
2011
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3264861/ https://www.ncbi.nlm.nih.gov/pubmed/22135037 http://dx.doi.org/10.1007/s13361-011-0295-5 |
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author | Song, Tao Hao, Qiang Law, Chun-Hin Siu, Chi-Kit Chu, Ivan K. |
author_facet | Song, Tao Hao, Qiang Law, Chun-Hin Siu, Chi-Kit Chu, Ivan K. |
author_sort | Song, Tao |
collection | PubMed |
description | In this study, we observed unprecedented cleavages of the C(β)–C(γ) bonds of tryptophan residue side chains in a series of hydrogen-deficient tryptophan-containing peptide radical cations (M(•+)) during low-energy collision-induced dissociation (CID). We used CID experiments and theoretical density functional theory (DFT) calculations to study the mechanism of this bond cleavage, which forms [M – 116](+) ions. The formation of an α-carbon radical intermediate at the tryptophan residue for the subsequent C(β)–C(γ) bond cleavage is analogous to that occurring at leucine residues, producing the same product ions; this hypothesis was supported by the identical product ion spectra of [LGGGH – 43](+) and [WGGGH – 116](+), obtained from the CID of [LGGGH](•+) and [WGGGH](•+), respectively. Elimination of the neutral 116-Da radical requires inevitable dehydrogenation of the indole nitrogen atom, leaving the radical centered formally on the indole nitrogen atom ([Ind](•)-2), in agreement with the CID data for [WGGGH](•+) and [W(1-CH3)GGGH](•+); replacing the tryptophan residue with a 1-methyltryptophan residue results in a change of the base peak from that arising from a neutral radical loss (116 Da) to that arising from a molecule loss (131 Da), both originating from C(β)–C(γ) bond cleavage. Hydrogen atom transfer or proton transfer to the γ-carbon atom of the tryptophan residue weakens the C(β)–C(γ) bond and, therefore, decreases the dissociation energy barrier dramatically. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s13361-011-0295-5) contains supplementary material, which is available to authorized users. |
format | Online Article Text |
id | pubmed-3264861 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2011 |
publisher | Springer-Verlag |
record_format | MEDLINE/PubMed |
spelling | pubmed-32648612012-02-03 Novel C(β)–C(γ) Bond Cleavages of Tryptophan-Containing Peptide Radical Cations Song, Tao Hao, Qiang Law, Chun-Hin Siu, Chi-Kit Chu, Ivan K. J Am Soc Mass Spectrom Research Article In this study, we observed unprecedented cleavages of the C(β)–C(γ) bonds of tryptophan residue side chains in a series of hydrogen-deficient tryptophan-containing peptide radical cations (M(•+)) during low-energy collision-induced dissociation (CID). We used CID experiments and theoretical density functional theory (DFT) calculations to study the mechanism of this bond cleavage, which forms [M – 116](+) ions. The formation of an α-carbon radical intermediate at the tryptophan residue for the subsequent C(β)–C(γ) bond cleavage is analogous to that occurring at leucine residues, producing the same product ions; this hypothesis was supported by the identical product ion spectra of [LGGGH – 43](+) and [WGGGH – 116](+), obtained from the CID of [LGGGH](•+) and [WGGGH](•+), respectively. Elimination of the neutral 116-Da radical requires inevitable dehydrogenation of the indole nitrogen atom, leaving the radical centered formally on the indole nitrogen atom ([Ind](•)-2), in agreement with the CID data for [WGGGH](•+) and [W(1-CH3)GGGH](•+); replacing the tryptophan residue with a 1-methyltryptophan residue results in a change of the base peak from that arising from a neutral radical loss (116 Da) to that arising from a molecule loss (131 Da), both originating from C(β)–C(γ) bond cleavage. Hydrogen atom transfer or proton transfer to the γ-carbon atom of the tryptophan residue weakens the C(β)–C(γ) bond and, therefore, decreases the dissociation energy barrier dramatically. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s13361-011-0295-5) contains supplementary material, which is available to authorized users. Springer-Verlag 2011-12-02 2012 /pmc/articles/PMC3264861/ /pubmed/22135037 http://dx.doi.org/10.1007/s13361-011-0295-5 Text en © The Author(s) 2011 https://creativecommons.org/licenses/by-nc/4.0/ This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited. |
spellingShingle | Research Article Song, Tao Hao, Qiang Law, Chun-Hin Siu, Chi-Kit Chu, Ivan K. Novel C(β)–C(γ) Bond Cleavages of Tryptophan-Containing Peptide Radical Cations |
title | Novel C(β)–C(γ) Bond Cleavages of Tryptophan-Containing Peptide Radical Cations |
title_full | Novel C(β)–C(γ) Bond Cleavages of Tryptophan-Containing Peptide Radical Cations |
title_fullStr | Novel C(β)–C(γ) Bond Cleavages of Tryptophan-Containing Peptide Radical Cations |
title_full_unstemmed | Novel C(β)–C(γ) Bond Cleavages of Tryptophan-Containing Peptide Radical Cations |
title_short | Novel C(β)–C(γ) Bond Cleavages of Tryptophan-Containing Peptide Radical Cations |
title_sort | novel c(β)–c(γ) bond cleavages of tryptophan-containing peptide radical cations |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3264861/ https://www.ncbi.nlm.nih.gov/pubmed/22135037 http://dx.doi.org/10.1007/s13361-011-0295-5 |
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