MALDI‐MS/MS of N‐Terminal TMPP‐Acyl Peptides: A Worthwhile Tool to Decipher Protein N‐Termini. Issue 21 (5th April 2022)

• Record Type: Journal Article
• Authors: Fernandez, Bernard; Armengaud, Jean; Subra, Gilles; Enjalbal, Christine
• Is Part Of: European journal of organic chemistry. Volume 2022:Issue 21(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-04-05
• Subjects: Mass spectrometry -- Peptides -- MS/MS -- MALDI-Tof/Tof -- TMPP-acylation; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.202101549
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract: N‐terminal derivatization of proteins with permanently positive charged reagent constitutes a viable mass spectrometry bottom‐up strategy for systematic confident identification of protein N‐termini. Although shotgun nanoLC‐ESI‐MS/MS approaches are commonly applied in that context by dissociating multiply charged molecular ions upon low energy collision‐induced dissociations (CID), we were keen to investigate an alternative sequencing method reckoning on more comprehensive high energy charge remote fragmentations (CRF) available with a MALDI‐Tof/Tof instrument. Hence, two tunable activation methods, i. e . metastable laser‐induced dissociations (LID) and high energy CID, were applied to several synthetic N‐terminal tris(trimethoxyphenyl)phosphonium (TMPP) acetyl peptides and their MS/MS behaviors were compared with low energy CID MS/MS data (LC‐ESI‐QqTof equipment). The amino acid composition was found to play a significant role in the peptide backbone dissociation pathways of these fixed singly charged ions. Proline, arginine, aspartic acid, glutamic acid, but also surprisingly aliphatic residues were impacting the expected sequence fragmentation pattern. Abstract : Acylation with tris(trimethoxyphenyl)phosphonium (TMPP), a chemical reagent specifically targeting peptide N‐termini, was found to provide very valuable sequencing information provided that the derivatized charged peptide was engaged in MALDI MS/MS analyses combining LID and CID activations. In addition to readable N‐terminal sequence ion series, fragmentation of aliphatic residues side‐chain distinguished isomeric leucine and isoleucine. Unexpected cysteine acylation was also evidenced.