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To b or not to b: The ongoing saga of peptide b ions

2009; Wiley; Volume: 28; Issue: 4 Linguagem: Inglês

10.1002/mas.20228

1098-2787

Alex G. Harrison,

Metabolomics and Mass Spectrometry Studies

Abstract Modern soft ionization techniques readily produce protonated or multiply protonated peptides. Collision‐induced dissociation (CID) of these protonated species is often used as a method to obtain sequence information. In many cases fragmentation occurs at amide bonds. When the charge resides on the C‐terminal fragment so‐called y ions are produced which are known to be protonated amino acids or truncated peptides. When the charge resides on the N‐terminal fragment so‐called b ions are produced. Often the sequence of y and b ions are essential for peptide sequencing. The b ions have many possible structures, a knowledge of which is useful in this sequencing. The structures of b ions are reviewed in the following with particular emphasis on the variation of structure with the number of amino acid residues in the b ion and the effect of peptide side chain on b ion structure. The recent discovery of full cyclization of larger b ions results in challenges in peptide sequencing. This aspect is discussed in detail. © 2009 Wiley Periodicals, Inc., Mass Spec Rev 28:640–654, 2009