Abstract
A nomenclature system for labeling fragment ions of cyclic peptides is proposed. A fragment ion is labeled with a four-part descriptor of the general formula x nJZ, where x is the designation for the ion (e. g., lower case a or b, as are used for peptide fragments) and n is the number of amino acid residues in the ion. A b ion is the usual acylium ion or isomeric equivalent consisting of n amino-acid residues, and this ion may lose carbon monoxide to form an a ion. The subscripts J and Z are the one-letter (upper-case) codes for the two amino-acid residues connecting the backbone amide or ester bond, J-Z, that can be viewed as broken to form the decomposing linear ion. The symbol J is for the N-terminal amino-acid residue, and Z is that for the C-terminal amino-acid residue that result from the bond cleavage. The nomenclature system is applicable to a wide range of cyclic peptides, including depsipeptides, cyclic peptides containing modified or unusual amino acids, cyclic peptides bearing a linear peptide moiety, and cyclic peptides that are introduced into the gas phase as metal-ion cationized species.
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References
Eckart, K. Mass Spectrometry of Cyclic Peptides. Mass Spectrom. Rev. 1994, 13, 23–55.
Roepstorff, P.; Fohlman, J. Proposal for a Common Nomenclature for Sequence Ions in Mass Spectra of Peptides. Biomed. Mass Spectrom. 1984, 11, 601.
Biemann, K. Nomenclature for Peptide Fragment Ions. In Methods in Enzymology; McCluskey, J. A., Ed.; Academic: Orlando, FL, 1990; Vol. 193, pp 886–888.
Tuinman, A. A.; Pettit, G. R. Analysis of the Amino Acid Sequence of Peptides by Mass Spectrometry. Int. J. Peptide Protein Res. 1990, 36, 331–334.
Gross, M. L. Tandem Mass Spectrometry: Multisector Magnetic Instruments. In Methods In Enzymology; McCloskey, J. A., Ed.; Academic: San Diego, 1990; Vol. 193, pp 131–153.
Ngoka, L. C. M.; Gross, M. L.; Toogood, P. L. Sodium-Directed Selective Cleavage of Lactones: A New Method for Structure Determination of Cyclodepsipeptide. Int. J. Mass Spectrom., in press.
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Ngoka, L.C.M., Gross, M.L. A nomenclature system for labeling cyclic peptide fragments. J Am Soc Mass Spectrom 10, 360–363 (1999). https://doi.org/10.1016/S1044-0305(99)00006-9
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DOI: https://doi.org/10.1016/S1044-0305(99)00006-9