4.3. Circular Dichroism (CD) Measurements

CD spectra of 150 µM peptides were measured at room temperature in 10 mM phosphate-buffered saline (PBS) (mimicking an aqueous environment), 50% TFE (mimicking the hydrophobic environment of the microbial membrane), and 30 mM SDS micelles (negatively charged prokaryotic membrane comparable environment) on a J-820 spectropolarimeter (Jasco; Tokyo, Japan), with a quartz cuvette with a 1.0-mm path length. The spectra were recorded from 195-250 nm at a scanning speed of 10 nm/min, and an average of 3 scans was collected for each peptide. The acquired CD spectra were then converted to the mean residue ellipticity with the following formula:

where θ_M is the mean residue ellipticity [(deg·cm²)/dmol], θ_obs is the observed ellipticity corrected for the buffer at a given wavelength [md, eg], c is the peptide concentration [mM], l is the path length [mm], and n is the number of amino acids.