Negative ion electrospray mass spectra of caerulein peptides: an aid to structural determination.
MS/MS data derived from the [M-H](-) ions of desulfated caerulein peptides provide (i) sequencing information from a combination of alpha, beta and gamma backbone cleavages, and (ii) identification of specific amino acid side chains by side-chain cleavages [e.g. Ser (-CH(2)O), Thr (-CH(3)CHO) and Asp (-H(2)O)] (fragmentations having no counterparts in positive ion spectra). In addition, delta and/or gamma backbone cleavage ions from Asp residues identify the position of these residues in the peptide. In contrast, neither delta nor gamma cleavage ions are observed from either the Gln2 residue nor from Phe residues. Full structural information can be obtained from a consideration of the positive and negative ion MS/MS data in concert.
Boontheung
Pinmanee
P
Department of Chemistry, The University of Adelaide, South Australia 5005, Australia.
Alewood
Paul F
PF
Brinkworth
Craig S
CS
Bowie
John H
JH
Wabnitz
Paul A
PA
Tyler
Michael J
MJ
D002108:Ceruletide / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D010455:Peptides / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization
D010455:Peptides; D002108:Ceruletide