1 mm high precision quartz cell

A JASCO J-815 CD spectrometer (Jasco, Essex, UK) was employed to perform the analysis of peptide secondary structures. Each peptide was dissolved in 10 mM ammonium acetate and 10 mM ammonium acetate with 50% TFE, respectively, to reach a concentration of 100 μM, in a 1 mm high precision quartz cell (Hellma Analytics, Essex, UK). All CD spectra were obtained at 20 °C from 250 nm to 190 nm at a scanning speed of 100 nm/min. The bandwidth was 1 nm, and the data pitch was 0.5 nm. K2D3 webserver [19 (link)] was used to estimate the α-helix content of the peptides from their CD spectrum data.

The sample peptide solutions (50 μM) were prepared in a 1 mm high precision quartz cell (Hellma Analytics, Essex, UK) with 10 mM ammonium acetate and 50% TFE in 10 mM ammonium acetate buffer respectively. CD measurements were performed at 20 °C by a JASCO J-815 CD spectrometer (Jasco, Essex, UK) across the wavelength range of 190–250 nm. The scanning speed was 100 nm/min, the bandwidth was one nm, and the data pitch was 0.5 nm. The CD spectra were further analysed using the online software, BeStSel [23 (link)], and the proportion of different secondary structures were predicted.

The secondary structure of each peptide was determined using a JASCO J-815 CD spectrometer (Jasco, Essex, UK). Each peptide was dissolved in 10 mM ammonium acetate and 10 mM ammonium acetate with 50% TFE, respectively and was prepared at 100 μM in a 1 mm high precision quartz cell (Hellma Analytics, Essex, UK). CD spectra were recorded at a wavelength ranging from 190 nm to 250 nm with a 100 nm/min scan speed. The parameters were set as 1 nm bandwidth and 0.5 nm data pitch. The result was analysed by the K2D3 webserver to estimate α-helical content [24 (link)]. The helical wheel projections and significant physiochemical parameters of peptides, were predicted by use of Network Protein Sequence Analysis [25 ] and Heliquest [26 ] programmes. The helical wheel projection was utilized to describe the properties of alpha helices as a visual plot [27 ]. The significant parameters such as hydrophobicity, hydrophobic moment, and net charge at neutral pH, which were considered as significant factors correlating with antimicrobial activity, antimicrobial spectrum, and haemolysis, were also predicted and calculated [28 (link),29 (link),30 (link),31 (link),32 ].