Peptide-based synthetic pulmonary surfactant for the treatment of respiratory distress disorders

- KL4 (sinapultide) was developed as a peptide replacement for surfactant protein B.
- Surfaxin, containing KL4, is the first clinically approved peptide-based pulmonary surfactant.
- KL4 differentially partitions into lipid bilayers in response to the degree of lipid saturation.
- KL4 helical structure varies with lipid saturation and pH.
- Adaptive partitioning and helicity may underpin the function of KL4 in pulmonary surfactant.