Membrane structure and interactions of a short Lycotoxin I analogue

• Published in: Journal of peptide science 2008-04, Vol.14 (4), p.528-534
• Main Authors: Adão, R., Seixas, R., Gomes, P., Pessoa, J. Costa, Bastos, M.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; anti-microbial peptide; Antimicrobial Cationic Peptides - chemical synthesis; Antimicrobial Cationic Peptides - chemistry; Araneae; Calorimetry, Differential Scanning; Candida glabrata; Circular Dichroism; DSC; Escherichia coli; ITC; Liposomes - chemistry; Lycosa; microcalorimetry; model membranes; Molecular Sequence Data; Phospholipids - chemistry; Spider Venoms - chemical synthesis; Spider Venoms - chemistry; Thermodynamics; Time Factors
• ISSN: 1075-2617; 1099-1387
• DOI: 10.1002/psc.993

Lycotoxin I and Lycotoxin II are natural anti‐microbial peptides that were identified in the venom of the Wolf Spider Lycosa carolinensis. These peptides were found to be potent growth inhibitors for bacteria (Escherichia coli) and yeast (Candida glabrata) at micromolar concentrations. Recently, shortened analogues of LycoI and LycoII have been reported to have decreased haemolytic effects. A shorter Lyco‐I analogue studied, LycoI 1–15 (H‐IWLTALKFLGKHAAK‐NH2), was active only above 10 µM, but was also the least haemolytic. On the basis of these findings, we became interested in obtaining a deeper insight into the membrane activity of LycoI 1–15, as this peptide may represent the first major step for the future development of selective, i.e. non‐haemolytic, Lycotoxin‐based antibiotics. The interaction of this peptide with liposomes of different composition was studied by microcalorimetry [differential scanning calorimetry (DSC) and isothermal titration calorimetry (ITC)] and CD. The results obtained from the calorimetric and spectroscopic techniques were jointly discussed in an attempt to further understand the interaction of this peptide with model membranes. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.