Far-UV circular dichroism datasets describing salt dependent secondary structure of Clostridioides difficile endolysin catalytic domains

This data article presents salt dependent far-UV circular dichroism datasets for the enzymatically active domains of two Clostridioides difficile –targeting bacteriophage endolysins, CD27L_EAD and PHICD111_20024_EAD. The dataset comprises sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) images documenting protein sample purity, far-UV circular dichroism spectra recorded from 195 to 260 nm, and secondary structure content estimates obtained by CDPro analysis over 195–240 nm. Circular dichroism measurements were performed at 25°C using 10 µM protein in 20 mM Tris-HCl (pH 7.0) containing 0, 50, 100, 150, and 200 mM NaF. For each protein and NaF condition, spectra were acquired as three consecutive scans of the same sample. Baseline-corrected spectra were converted to mean residue ellipticity. The resulting mean residue ellipticity data were averaged for visualization, and α-helical content was estimated by CDPro analysis of each scan over 195–240 nm. The repository provides instrument-exported CSV files containing wavelength-resolved circular dichroism signals in millidegrees together with acquisition information. Processed mean residue ellipticity datasets (Excel files), CDPro/CDSSTR output files (.out), and summary tables of α-helical content are also provided. SDS-PAGE images documenting sample purity are presented as figures in this article.