Discrimination of Isoleucine and Leucine by Dimethylation-Assisted MS3

Sheila Maibom-Thomsen, Søren Heissel, Ejvind Mørtz, Peter Højrup, Jakob Bunkenborg

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Abstract

Protein sequencing by mass spectrometry has transformed the field of biopharmaceutical analysis, but a missing part in the analytical toolkit is the ability to distinguish between the isomeric residues isoleucine and leucine because it is a requisite for efficient analysis of the primary structure of proteins. To address this need, we have developed a novel mass spectrometric method that combines reductive dimethylation and MS3 fragmentation with LCMS peptide mapping. The dimethylation of peptide N-termini leads to intense a1-ions upon collision-induced fragmentation, and further fragmentation of the isoleucine/leucine a1-ion leads to informative spectra with fragments that can discriminate between the two isomers. The methodology of a1-directed MS3 was applied to two antibodies in combination with the proteases trypsin, thermolysin, chymotrypsin, and pepsin to generate peptides exposing N-terminal I/L residues.

Original languageEnglish
JournalAnalytical Chemistry
Volume90
Issue number15
Pages (from-to)9055–9059
ISSN0003-2700
DOIs
Publication statusPublished - 2018

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Isoleucine
Leucine
Peptides
Ions
Thermolysin
Pepsin A
Chymotrypsin
Isomers
Trypsin
Mass spectrometry
Proteins
Peptide Hydrolases
Antibodies

Cite this

Maibom-Thomsen, Sheila ; Heissel, Søren ; Mørtz, Ejvind ; Højrup, Peter ; Bunkenborg, Jakob. / Discrimination of Isoleucine and Leucine by Dimethylation-Assisted MS3. In: Analytical Chemistry. 2018 ; Vol. 90, No. 15. pp. 9055–9059.
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title = "Discrimination of Isoleucine and Leucine by Dimethylation-Assisted MS3",
abstract = "Protein sequencing by mass spectrometry has transformed the field of biopharmaceutical analysis, but a missing part in the analytical toolkit is the ability to distinguish between the isomeric residues isoleucine and leucine because it is a requisite for efficient analysis of the primary structure of proteins. To address this need, we have developed a novel mass spectrometric method that combines reductive dimethylation and MS3 fragmentation with LCMS peptide mapping. The dimethylation of peptide N-termini leads to intense a1-ions upon collision-induced fragmentation, and further fragmentation of the isoleucine/leucine a1-ion leads to informative spectra with fragments that can discriminate between the two isomers. The methodology of a1-directed MS3 was applied to two antibodies in combination with the proteases trypsin, thermolysin, chymotrypsin, and pepsin to generate peptides exposing N-terminal I/L residues.",
author = "Sheila Maibom-Thomsen and S{\o}ren Heissel and Ejvind M{\o}rtz and Peter H{\o}jrup and Jakob Bunkenborg",
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Maibom-Thomsen, S, Heissel, S, Mørtz, E, Højrup, P & Bunkenborg, J 2018, 'Discrimination of Isoleucine and Leucine by Dimethylation-Assisted MS3', Analytical Chemistry, vol. 90, no. 15, pp. 9055–9059. https://doi.org/10.1021/acs.analchem.8b01375

Discrimination of Isoleucine and Leucine by Dimethylation-Assisted MS3. / Maibom-Thomsen, Sheila; Heissel, Søren; Mørtz, Ejvind; Højrup, Peter; Bunkenborg, Jakob.

In: Analytical Chemistry, Vol. 90, No. 15, 2018, p. 9055–9059.

Research output: Contribution to journalJournal articleResearchpeer-review

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T1 - Discrimination of Isoleucine and Leucine by Dimethylation-Assisted MS3

AU - Maibom-Thomsen, Sheila

AU - Heissel, Søren

AU - Mørtz, Ejvind

AU - Højrup, Peter

AU - Bunkenborg, Jakob

PY - 2018

Y1 - 2018

N2 - Protein sequencing by mass spectrometry has transformed the field of biopharmaceutical analysis, but a missing part in the analytical toolkit is the ability to distinguish between the isomeric residues isoleucine and leucine because it is a requisite for efficient analysis of the primary structure of proteins. To address this need, we have developed a novel mass spectrometric method that combines reductive dimethylation and MS3 fragmentation with LCMS peptide mapping. The dimethylation of peptide N-termini leads to intense a1-ions upon collision-induced fragmentation, and further fragmentation of the isoleucine/leucine a1-ion leads to informative spectra with fragments that can discriminate between the two isomers. The methodology of a1-directed MS3 was applied to two antibodies in combination with the proteases trypsin, thermolysin, chymotrypsin, and pepsin to generate peptides exposing N-terminal I/L residues.

AB - Protein sequencing by mass spectrometry has transformed the field of biopharmaceutical analysis, but a missing part in the analytical toolkit is the ability to distinguish between the isomeric residues isoleucine and leucine because it is a requisite for efficient analysis of the primary structure of proteins. To address this need, we have developed a novel mass spectrometric method that combines reductive dimethylation and MS3 fragmentation with LCMS peptide mapping. The dimethylation of peptide N-termini leads to intense a1-ions upon collision-induced fragmentation, and further fragmentation of the isoleucine/leucine a1-ion leads to informative spectra with fragments that can discriminate between the two isomers. The methodology of a1-directed MS3 was applied to two antibodies in combination with the proteases trypsin, thermolysin, chymotrypsin, and pepsin to generate peptides exposing N-terminal I/L residues.

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DO - 10.1021/acs.analchem.8b01375

M3 - Journal article

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SP - 9055

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JO - Analytical Chemistry

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SN - 0003-2700

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