Secondary structure and lipid interactions of the N-terminal segment of pulmonary surfactant SP-C in langmuir films

IR reflection-absorption spectroscopy and surface pressure studies

Xiaohong Bi, Carol R. Flach, Jesus Pérez-Gil, Inés Plasencia, David Andreu, Eliandre Oliveira, Richard Mendelsohn

Research output: Contribution to journalArticle

61 Citations (Scopus)

Abstract

Pulmonary surfactant, a thin lipid/protein film lining mammalian lungs, functions in vivo to reduce the work of breathing and to prevent alveolar collapse. Analogues of two hydrophobic surfactant proteins, SP-B and SP-C, have been incorporated into therapeutic agents for respiratory distress syndrome, a pathological condition resulting from deficiency in surfactant. To facilitate rational design of therapeutic agents, a molecular level understanding of lipid interaction with surfactant proteins or their analogues in aqueous monolayer films is necessary. The current work uses infrared reflection-absorption spectroscopy (IRRAS) to determine peptide conformation and the effects of S-palmitoylation on the lipid interactions of a synthetic 13 residue N-terminal peptide [SP-C13(palm)2] of SP-C, in mixtures with 1,2-dipalmitoylphosphatidylcholine (DPPC) or 1,2-dipalmitoylphosphatidylglycerol (DPPG). Two Amide I′ features, at ∼1655 and ∼1639 cm-1 in the peptide IRRAS spectra, are assigned to α-helical peptide bonds in hydrophobic and aqueous environments, respectively. In binary DPPC/SP-C13(palm)2 films, the proportion of hydrated/hydrophobic helix increases reversibly with surface pressure (π), suggestive of the peptide being squeezed out from hydrophobic regions of the monolayer. No such effect was observed for DPPG/peptide monolayers, indicative of stronger, probably electrostatic, interactions. Depalmitoylation produced a weakened interaction with either phospholipid as deduced from IRRAS spectra and from π-area isotherms. S-Palmitoylation may modulate peptide hydration and conformation in the N-terminal region of SP-C and may thus permit the peptide to remain in the film at the high surface pressures present during lung compression. The unique capability of IRRAS to detect the surface pressure dependence of protein or peptide structure/interactions in a physiologically relevant model for surfactant is clearly demonstrated.

Original languageEnglish (US)
Pages (from-to)8385-8395
Number of pages11
JournalBiochemistry
Volume41
Issue number26
DOIs
StatePublished - Jul 2 2002

Fingerprint

Pulmonary Surfactants
Langmuir Blodgett films
Absorption spectroscopy
Spectrum Analysis
Lipids
Pressure
Peptides
Surface-Active Agents
Lipoylation
1,2-Dipalmitoylphosphatidylcholine
Infrared radiation
Monolayers
Pulmonary Surfactant-Associated Protein B
Conformations
Work of Breathing
Lung
Proteins
Static Electricity
Amides
Coulomb interactions

All Science Journal Classification (ASJC) codes

  • Biochemistry

Cite this

Bi, Xiaohong ; Flach, Carol R. ; Pérez-Gil, Jesus ; Plasencia, Inés ; Andreu, David ; Oliveira, Eliandre ; Mendelsohn, Richard. / Secondary structure and lipid interactions of the N-terminal segment of pulmonary surfactant SP-C in langmuir films : IR reflection-absorption spectroscopy and surface pressure studies. In: Biochemistry. 2002 ; Vol. 41, No. 26. pp. 8385-8395.
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abstract = "Pulmonary surfactant, a thin lipid/protein film lining mammalian lungs, functions in vivo to reduce the work of breathing and to prevent alveolar collapse. Analogues of two hydrophobic surfactant proteins, SP-B and SP-C, have been incorporated into therapeutic agents for respiratory distress syndrome, a pathological condition resulting from deficiency in surfactant. To facilitate rational design of therapeutic agents, a molecular level understanding of lipid interaction with surfactant proteins or their analogues in aqueous monolayer films is necessary. The current work uses infrared reflection-absorption spectroscopy (IRRAS) to determine peptide conformation and the effects of S-palmitoylation on the lipid interactions of a synthetic 13 residue N-terminal peptide [SP-C13(palm)2] of SP-C, in mixtures with 1,2-dipalmitoylphosphatidylcholine (DPPC) or 1,2-dipalmitoylphosphatidylglycerol (DPPG). Two Amide I′ features, at ∼1655 and ∼1639 cm-1 in the peptide IRRAS spectra, are assigned to α-helical peptide bonds in hydrophobic and aqueous environments, respectively. In binary DPPC/SP-C13(palm)2 films, the proportion of hydrated/hydrophobic helix increases reversibly with surface pressure (π), suggestive of the peptide being squeezed out from hydrophobic regions of the monolayer. No such effect was observed for DPPG/peptide monolayers, indicative of stronger, probably electrostatic, interactions. Depalmitoylation produced a weakened interaction with either phospholipid as deduced from IRRAS spectra and from π-area isotherms. S-Palmitoylation may modulate peptide hydration and conformation in the N-terminal region of SP-C and may thus permit the peptide to remain in the film at the high surface pressures present during lung compression. The unique capability of IRRAS to detect the surface pressure dependence of protein or peptide structure/interactions in a physiologically relevant model for surfactant is clearly demonstrated.",
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Secondary structure and lipid interactions of the N-terminal segment of pulmonary surfactant SP-C in langmuir films : IR reflection-absorption spectroscopy and surface pressure studies. / Bi, Xiaohong; Flach, Carol R.; Pérez-Gil, Jesus; Plasencia, Inés; Andreu, David; Oliveira, Eliandre; Mendelsohn, Richard.

In: Biochemistry, Vol. 41, No. 26, 02.07.2002, p. 8385-8395.

Research output: Contribution to journalArticle

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T1 - Secondary structure and lipid interactions of the N-terminal segment of pulmonary surfactant SP-C in langmuir films

T2 - IR reflection-absorption spectroscopy and surface pressure studies

AU - Bi, Xiaohong

AU - Flach, Carol R.

AU - Pérez-Gil, Jesus

AU - Plasencia, Inés

AU - Andreu, David

AU - Oliveira, Eliandre

AU - Mendelsohn, Richard

PY - 2002/7/2

Y1 - 2002/7/2

N2 - Pulmonary surfactant, a thin lipid/protein film lining mammalian lungs, functions in vivo to reduce the work of breathing and to prevent alveolar collapse. Analogues of two hydrophobic surfactant proteins, SP-B and SP-C, have been incorporated into therapeutic agents for respiratory distress syndrome, a pathological condition resulting from deficiency in surfactant. To facilitate rational design of therapeutic agents, a molecular level understanding of lipid interaction with surfactant proteins or their analogues in aqueous monolayer films is necessary. The current work uses infrared reflection-absorption spectroscopy (IRRAS) to determine peptide conformation and the effects of S-palmitoylation on the lipid interactions of a synthetic 13 residue N-terminal peptide [SP-C13(palm)2] of SP-C, in mixtures with 1,2-dipalmitoylphosphatidylcholine (DPPC) or 1,2-dipalmitoylphosphatidylglycerol (DPPG). Two Amide I′ features, at ∼1655 and ∼1639 cm-1 in the peptide IRRAS spectra, are assigned to α-helical peptide bonds in hydrophobic and aqueous environments, respectively. In binary DPPC/SP-C13(palm)2 films, the proportion of hydrated/hydrophobic helix increases reversibly with surface pressure (π), suggestive of the peptide being squeezed out from hydrophobic regions of the monolayer. No such effect was observed for DPPG/peptide monolayers, indicative of stronger, probably electrostatic, interactions. Depalmitoylation produced a weakened interaction with either phospholipid as deduced from IRRAS spectra and from π-area isotherms. S-Palmitoylation may modulate peptide hydration and conformation in the N-terminal region of SP-C and may thus permit the peptide to remain in the film at the high surface pressures present during lung compression. The unique capability of IRRAS to detect the surface pressure dependence of protein or peptide structure/interactions in a physiologically relevant model for surfactant is clearly demonstrated.

AB - Pulmonary surfactant, a thin lipid/protein film lining mammalian lungs, functions in vivo to reduce the work of breathing and to prevent alveolar collapse. Analogues of two hydrophobic surfactant proteins, SP-B and SP-C, have been incorporated into therapeutic agents for respiratory distress syndrome, a pathological condition resulting from deficiency in surfactant. To facilitate rational design of therapeutic agents, a molecular level understanding of lipid interaction with surfactant proteins or their analogues in aqueous monolayer films is necessary. The current work uses infrared reflection-absorption spectroscopy (IRRAS) to determine peptide conformation and the effects of S-palmitoylation on the lipid interactions of a synthetic 13 residue N-terminal peptide [SP-C13(palm)2] of SP-C, in mixtures with 1,2-dipalmitoylphosphatidylcholine (DPPC) or 1,2-dipalmitoylphosphatidylglycerol (DPPG). Two Amide I′ features, at ∼1655 and ∼1639 cm-1 in the peptide IRRAS spectra, are assigned to α-helical peptide bonds in hydrophobic and aqueous environments, respectively. In binary DPPC/SP-C13(palm)2 films, the proportion of hydrated/hydrophobic helix increases reversibly with surface pressure (π), suggestive of the peptide being squeezed out from hydrophobic regions of the monolayer. No such effect was observed for DPPG/peptide monolayers, indicative of stronger, probably electrostatic, interactions. Depalmitoylation produced a weakened interaction with either phospholipid as deduced from IRRAS spectra and from π-area isotherms. S-Palmitoylation may modulate peptide hydration and conformation in the N-terminal region of SP-C and may thus permit the peptide to remain in the film at the high surface pressures present during lung compression. The unique capability of IRRAS to detect the surface pressure dependence of protein or peptide structure/interactions in a physiologically relevant model for surfactant is clearly demonstrated.

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