Inhibition of bacterial growth by synthetic SP-B1-78 peptides.

Residues 12-34 of mature human pulmonary surfactant protein B (SP-B1-78) are 68% homologous to residues 48-72 of the frog peptide antibiotic dermaseptin b I. We examined the effects of SP-B1-78 on the growth of Escherichia coli in order to find whether full length SP-B1-78 might act as a peptide antibiotic. We found that SP-B1-78 peptide inhibited growth of E. coli (MIC = 210 micrograms.ml-1), but that the SP-B variant [R/K-->S]SP-B1-78 was less potent (MIC = 500 micrograms.ml-1).