Surfactant protein B: lipid interactions of synthetic peptides representing the amino-terminal amphipathic domain.
The mechanisms by which pulmonary surfactant protein B (SP-B) affects the surface activity of surfactant lipids are unclear. We have studied the peptide/lipid interactions of the amino-terminal amphipathic domain of SP-B by comparing the secondary conformations and surface activities of a family of synthetic peptides based on the native human SP-B sequence, modified by site-specific amino acid substitutions. Circular dichroism measurements show an alpha-helical structure correlating with the ability of the peptides to interact with lipids and with the surface activity of peptide/lipid dispersions. Amino acid substitutions altering either the charge or the hydrophobicity of the residues lowered the helical content and reduced the association of the aminoterminal segment with lipid dispersions. Surface activity of peptide/lipid mixtures was maximally altered by reversal of charge in synthetic peptides. These observations indicate that electrostatic interactions and hydrophobicity are important factors in determining optimal structure and function of surfactant peptides in lipid dispersions.
Bruni
R
R
Department of Pediatrics, King/Drew Medical Center, University of California School of Medicine, Los Angeles 90059.
Taeusch
H W
HW
Waring
A J
AJ
D015060:1,2-Dipalmitoylphosphatidylcholine / Q000378:metabolism; D000588:Amines / Q000378:metabolism; D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D005583:Fourier Analysis; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D050356:Lipid Metabolism; D008969:Molecular Sequence Data; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000378:metabolism; D010455:Peptides / Q000138:chemical synthesis / Q000302:isolation & purification / Q000378:metabolism; D010715:Phosphatidylglycerols / Q000378:metabolism; D011487:Protein Conformation; D011510:Proteolipids / Q000138:chemical synthesis / Q000378:metabolism*; D011663:Pulmonary Surfactants / Q000138:chemical synthesis / Q000378:metabolism*; D013055:Spectrophotometry, Infrared; D013500:Surface Tension
D000588:Amines; D006023:Glycoproteins; D010169:Palmitic Acids; D010455:Peptides; D010715:Phosphatidylglycerols; D011510:Proteolipids; D011663:Pulmonary Surfactants; D015060:1,2-Dipalmitoylphosphatidylcholine; D019308:Palmitic Acid; C009317:stearylamine