The structure of antimicrobial pexiganan peptide in solution probed by Fourier transform infrared absorption, vibrational circular dichroism, and electronic circular dichroism spectroscopy

✍ Scribed by Ganesh Shanmugam; Prasad L. Polavarapu; D. Gopinath; R. Jayakumar

• Publisher: Wiley (John Wiley & Sons)
• Year: 2005
• Tongue: English
• Weight: 103 KB
• Volume: 80
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.20132

✦ Synopsis

Abstract

Pexiganan (Gly–Ile–Gly–Lys–Phe–Leu–Lys–Lys–Ala–Lys–Lys–Phe–Gly–Lys–Ala–Phe–Val–Lys–Ile–Leu–Lys–Lys), a 22 amino acid peptide, is an analogue of the magainin family of antimicrobial peptides present in the skin of the African clawed frog. Conformational analysis of pexiganan was carried out in different solvent environments for the first time. Organic solvents, trifluoroethanol (TFE) and methanol, were used to study the secondary structural preferences of this peptide in the membrane‐mimicking environments. In addition, aqueous (D~2~O) and dimethyl sulfoxide (DMSO) solutions were also investigated to study the role of hydrogen bonding involved in the secondary structure formation. Fourier transform infrared absorption, vibrational circular dichroism (VCD), and electronic circular dichroism (ECD) measurements were carried out under the same conditions to ascertain the conformational assignments in different solvents. All these spectroscopic measurements suggest that the pexiganan peptide has the tendency to adopt different structures in different environments. Pexiganan appears to adopt an α‐helical conformation in TFE, a sheet‐stabilized β‐turn structure in methanol, a random coil with β‐turn structure in D~2~O, and a solvated β‐turn structure in DMSO. © 2005 Wiley Periodicals, Inc. Biopolymers (Pept Sci), 2005