In peptide sequencing experiments involving a single step tandem mass acquisition, leucine and isoleucine are indistinguishable because both are characterized by a 113 Da mass difference from the other peptide fragments in the MS2 spectrum. In this work, we propose a new method to distinguish between these two amino acids in consecutive MSn experiments, exploiting a gas-phase fragmentation of isoleucine that leads to a diagnostic 69 Da ion. We used this method to assess the Leu/Ile residues of several synthetic peptides. The procedure was then tested on a tryptic digest of myoglobin, assigning the correct amino acid in the majority of the peptides. This work was performed with an old and low-resolution instrument, thus demonstrating that our method is suitable for a wide number of ion trap mass spectrometers not necessarily expensive or up-to-date.

How to Discriminate Between Leucine and Isoleucine by Low Energy ESI-TRAP MS(n) / ARMIROTTI A; MILLO E; G. DAMONTE. - In: JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY. - ISSN 1044-0305. - STAMPA. - 18(1)(2007), pp. 57-63.

How to Discriminate Between Leucine and Isoleucine by Low Energy ESI-TRAP MS(n)

MILLO, ENRICO;DAMONTE, GIANLUCA
2007

Abstract

In peptide sequencing experiments involving a single step tandem mass acquisition, leucine and isoleucine are indistinguishable because both are characterized by a 113 Da mass difference from the other peptide fragments in the MS2 spectrum. In this work, we propose a new method to distinguish between these two amino acids in consecutive MSn experiments, exploiting a gas-phase fragmentation of isoleucine that leads to a diagnostic 69 Da ion. We used this method to assess the Leu/Ile residues of several synthetic peptides. The procedure was then tested on a tryptic digest of myoglobin, assigning the correct amino acid in the majority of the peptides. This work was performed with an old and low-resolution instrument, thus demonstrating that our method is suitable for a wide number of ion trap mass spectrometers not necessarily expensive or up-to-date.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11567/249618
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