peptide antibiotic BPI PDB:1EWF Bactericidal/permeability-increasing (BPI) protein is a member of a new generation of proteins known as super-antibiotics that are implicated as endotoxin neutralising agents. The potent (nM) cytotoxicity of BPI is limited to gram-negative bacteria (GNB), reflecting the high affinity (<10 nM) of BPI for bacterial lipopolysaccharides (LPS). Binding of BPI to live bacteria via LPS causes immediate growth arrest, actual killing coincides with later damage to the inner membrane. ARO:3004121 antibiotic_resistance