Supplementary Code

This archive contains the scripts used for the main analytical steps of the study

Pipeline overview:
1) Sequence-level feature extraction:
   Scripts in "percentage and frequency in FASTA" were used to calculate the
   frequency and percentage of histidine residues from protein FASTA files.

2) pKa-based feature extraction:
   Scripts in "codes for propka" were used to run PROPKA 3.0 in batch mode,
   extract the SUMMARY section from PROPKA outputs, and retain ionizable residues
   with predicted pKa values in the 6.0–7.2 range.

3) α-helix identification:
   Scripts in "helix-range-generator" were used to extract α-helical residue ranges
   from HELIX records in PDB files.

Additional generic scripts and limited manual inspection were used only for data
organization and cleaning of intermediate CSV files. These steps did not affect
the analytical logic or feature definitions.

Requirements:
- PROPKA 3.0
- pdb-tools (pdb_fetch, pdb_selres)
- Standard Unix tools (bash, awk, grep, sed)
