CD and NMR structural characterization of ceratotoxins, natural peptides with antimicrobial activity

✍ Scribed by Laura Ragona; Henriette Molinari; Lucia Zetta; Renato Longhi; Daniela Marchini; Romano Dallai; Luigi F. Bernini; Luisa Lozzi; Maria Scarselli; Neri Niccolai

• Publisher: Wiley (John Wiley & Sons)
• Year: 1998
• Tongue: English
• Weight: 829 KB
• Volume: 39
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/(sici)1097-0282(199611)39:5<653::aid-bip4>3.0.co;2-v

✦ Synopsis

Antibacterial properties of the secretion from the female reproductive accessoryglands of medfry Ceratitis capitata are mostly ascribed to the presence of two peptides, ceratotoxin A and B, which exhibit a strong activity against gram-positive and gram-negative bacterial strains, and show sequence and function homology with cecropins, melittin, and magainins.

CD experiments performed in different solvents indicate the presence of a sign.$cant content of helical structures in organic solvent.

Twvdimensional nmr results for ceratotoxin A in methanol show a helical behaviorfor the 8-25 region of the peptide. A Ramachandran classijication of each residue for the structures obtained .from distance geometry calculations lead to the definition of four structural families in which the central segment 10-1 9 is always helical and differences refer to residues 8-9 and 19-23.

A sequence analysis of the two ceratotoxins and a systematic search on the protein data bank revealed the occurrence of a KX-hydrophobic-hydrophobic-P motif that seems to be important for helix stabilization.