Interfacial Behavior of Recombinant Forms of Human Pulmonary Surfactant Protein SP-C

• Published in: Langmuir Vol. 28; no. 20; pp. 7811 - 7825
• Main Authors: Lukovic, Dunja, Cruz, Antonio, Gonzalez-Horta, Azucena, Almlen, Andrea, Curstedt, Tore, Mingarro, Ismael, Pérez-Gil, Jesus
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 22.05.2012
• Subjects: Amino Acid Sequence; Animals; Catalysis; Chemistry; Exact sciences and technology; General and physical chemistry; Humans; Medicin och hälsovetenskap; Models, Molecular; Molecular Sequence Data; Peptide Fragments - chemistry; Peptide Fragments - metabolism; Phospholipids - chemistry; Phospholipids - metabolism; Protein Conformation; Pulmonary Surfactant-Associated Protein C - chemistry; Pulmonary Surfactant-Associated Protein C - metabolism; Recombinant Proteins - chemistry; Recombinant Proteins - metabolism; Surface physical chemistry; Surface Properties; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Human; Compression; Catalytic reaction; Phenylalanine; Film; Lung; Phospholipid; Lipids; Air; Surfactant; Orientation; Condensation; Bilayer; Protein; High pressure; Liquid; Adsorption; Dynamics; Isotherm; Surface pressure; Hysteresis; Interface; Conformation
• ISSN: 0743-7463; 1520-5827; 1520-5827
• DOI: 10.1021/la301134v

The behavior at air–liquid interfaces of two recombinant versions of human surfactant protein SP-C has been characterized in comparison with that of native palmitoylated SP-C purified from porcine lungs. Both native and recombinant proteins promoted interfacial adsorption of dipalmitoylphosphatidylcholine bilayers to a limited extent, but catalyzed very rapid formation of films from different lipid mixtures containing both zwitterionic and anionic phospholipids. Once at the interface, the recombinant variants exhibited compression-driven structural transitions, consistent with changes in the orientation of the deacylated N-terminal segment, which were not observed in the native protein. Compression isotherms of lipid/protein films suggest that the recombinant SP-C forms promote expulsion at high pressures of a higher number of lipid molecules per mole of protein than does native SP-C. A more dynamic conformation of the N-terminal segment in recombinant SP-C forms is likely also responsible for facilitating compression-driven condensation of domains in anionic phospholipid films as observed by epifluorescence microscopy. Finally, both native palmitoylated SP-C and the phenylalanine-containing recombinant versions facilitate similarly the repetitive compression–expansion dynamics of lipid/protein films, which were able to reach maximal surface pressures with practically no hysteresis along multiple quasi-static or dynamic cycles.