Surfactant preparations obtained from porcine lungs by extraction with chloroform/methanol followed by chromatography over Lipidex-5000 are used for treatment of respiratory distress syndrome in preterm infants. These preparations contain about 98% phospholipids and 1-2% of the hydrophobic pulmonary surfactant-associated proteins B and C (SP-B and SP-C). Separation of the proteins in the surfactant preparation by reversed-phase high performance liquid chromatography revealed, in addition to SP-B and SP-C, the presence of three peptides derived from the cathelicidin family of antibacterial peptides. The 79-residue proline-rich peptide prophenin (identical to that isolated from leukocytes), an 80-residue prophenin with an N-terminal pyroglutamic acid residue, and a C-terminal 18-residue fragment of prophenin were found in approximate molar ratios of 1:20:5. A synthetic version of the C-terminal 18-residue peptide exhibits salt-dependent antibacterial activity (higher activity in the absence of salt) against the Gram-positive bacterium Bacillus megaterium Bm11 and, to a lesser extent, against Gram-negative Escherichia coli D21 cells. It appears possible that the presence of prophenin peptides may contribute to the antibacterial properties of surfactant preparations. Copyright (C) 1999 Federation of European Biochemical Societies.
Wang, Y., Griffiths, W. J., Curstedt, T., & Johansson, J. (1999). Porcine pulmonary surfactant preparations contain the antibacterial peptide prophenin and a C-terminal 18-residue fragment thereof. FEBS Letters, 460(2), 257–262. https://doi.org/10.1016/S0014-5793(99)01363-0