title: CD and FTIR studies of an immunogenic disulphide cyclized octadecapeptide, a fragment of a snake curaremimetic toxin.
abstract: In a previous paper, the systematic epitope screening of a snake curaremimetic toxin or toxin a was described by this group using a panel of synthetic octadecapeptides. The disulphide cyclized peptide (Cys-23,40)(23-40) corresponding to loop II of the native toxin was found to elicit, with no linkage to a carrier, neutralizing antisera against the toxin. We have now undertaken the conformational study of this immunogenic disulphide cyclized peptide by CD and FTIR. The CD study of the peptide was carried in aqueous solution under various conditions (pH, temperature, presence of micelles) and in trifluoroethanol solution. Low temperature, SDS micelles and trifluoroethanol were found to induce a beta-sheet formation (16 to 39%). FTIR spectra of the peptide in the solid state (dry film) and in D2O solution or deuterated-TFE solution (hydrated film) displayed some characteristic bands indicating the presence of beta-sheet (1623 cm-1) and beta-turn (1637 cm-1; 1694 cm-1). These studies indicate that the immunogenic disulphide cyclized peptide (23-40) can adopt in solution an ordered structure.
authors.affiliation: Département d'Ingénierie et d'Etudes des Protéines, CE Saclay, Gif sur Yvette, France.
authors.forename: H
authors.initials: H
authors.lastname: Lamthanh
authors.forename: M
authors.initials: M
authors.lastname: Léonetti
authors.forename: E
authors.initials: E
authors.lastname: Nabedryk
authors.forename: A
authors.initials: A
authors.lastname: Ménez
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002942:Circular Dichroism; D003039:Cobra Neurotoxin Proteins / Q000737:chemistry* / Q000276:immunology; D003472:Curare / Q000737:chemistry* / Q000276:immunology; D004220:Disulfides / Q000737:chemistry*; D005583:Fourier Analysis; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D010446:Peptide Fragments / Q000737:chemistry*; D010456:Peptides, Cyclic / Q000737:chemistry*; D011487:Protein Conformation; D012996:Solutions; D013696:Temperature
chemical_list: D003039:Cobra Neurotoxin Proteins; D004220:Disulfides; D010446:Peptide Fragments; D010456:Peptides, Cyclic; D012996:Solutions; C085058:alpha-cobratoxin cyclic peptide Cys-23,40 (23-40); C025154:alpha-cobratoxin; D003472:Curare