In this work we employed UV resonance Raman spectroscopy with 229 nm excitation to study two tryptophan-containing antimicrobial peptides with a broad-spectrum activity against Gram-positive and Gram-negative bacteria: lactoferricin B (LfB, RRWQWRMKKLG) and pEM-2 (KKWRWWLKALAKK). UV resonance Raman spectra of both peptides are dominated by tryptophan bands. Raman spectra of LfB and pEM-2 in D2O and 2,2,2-trifluoro ethanol (TFE) have been measured and used to identify the hydrogen-bond strength marker bands W6 and W17. The tryptophan doublet, W7, at 1340 and 1360 cm-1 was used to detect an increase in the hydrophobicity of Trp environment in TFE. The spectra of LfB in complex with model cell membranes composed of zwitterionic dipalmitoylglycero-phosphocholine (DPPC) or anionic dipalmitoyglycero- phosphoglycerol (DPPG) lipid vesicles revealed a more hydrophobic Trp environment in DPPG, suggesting stronger interactions between the cationic peptide and anionic model cell membrane. Copyright

Antimicrobial peptide, Model cell membrane, UV resonance Raman
Journal of Raman Spectroscopy
Department of Chemistry

Quan, B. (Bryan), & Ianoul, A.I. (2009). UV resonance Raman spectroscopy probes the localization of tryptophan-containing antimicrobial peptides in lipid vesicles. Journal of Raman Spectroscopy, 40(3), 260–263. doi:10.1002/jrs.2116