Backbone cleavages of [M - H](-) anions derived from caerin 1 peptides and some synthetic modifications. Molecular recognition initiating internal cyclisation of Glu23.
The collision induced spectra of [M - H](-) anions from of caerin 1 peptides and some synthetic modifications show the usual alpha, beta and beta' backbone cleavages together with Ser (epsilon,gamma) and Glu (gamma) cleavages which break the peptide backbone in the vicinity of those residues. All of these cleavages require the peptide backbone to be flexible. There is also a backbone cleavage of a type not observed before. This cleavage involves nucleophilic attack of the carboxylate anion of the Glu23 side chain at the backbone CH of Ile 21. We propose that this cleavage requires the caerin peptide to be in an alpha helical conformation (the 3D structure that this peptide adopts in solution) in order that the interacting groups are held in close proximity.
Department of Chemistry, The University of Adelaide, South Australia, 5005.
Craig S
CS
Brinkworth
John H
JH
Bowie
D000595:Amino Acid Sequence; D029845:Amphibian Proteins; D000663:Amphibians; D000818:Animals; D000838:Anions; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry*; D003500:Cyclization; D018698:Glutamic Acid / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010446:Peptide Fragments / Q000737:chemistry; D017433:Protein Structure, Secondary; D016339:Spectrometry, Mass, Fast Atom Bombardment
D029845:Amphibian Proteins; D000838:Anions; D023181:Antimicrobial Cationic Peptides; D010446:Peptide Fragments; C107616:caerin 1.1, Anura; D018698:Glutamic Acid