Hydrophobic homopolymeric peptides enhance the biophysical activity of synthetic lung phospholipids

A. R. Venkitaraman, Stephen (Steve) Hall, R. H. Notter

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

The effects of homopolymeric amino acids (molecular weight 2300 to 14,000) on the surface activity of dipalmitoyl phosphatidylcholine (DPPC) and DPPC/egg-phosphatidylglycerol (PG) were characterized by adsorption and dynamic surface tension lowering measurements at 37°C. Homopolyamino acids studied included polyl-leucine (poly-Leu) and poly-l-valine (poly-Val), since Leu and Val are known to be prominent in the structure of hydrophobic lung surfactant apoprotein SP-B and SP-C. In addition, several other homopolyamino acids with varying hydrophobicity index were also investigated, including poly-l-phenylalanine (poly-Phe), poly-l-serine (poly-Ser), poly-l-lysine (poly-Lys) and poly-l-glutamic acid (poly-Glu). Results showed that hydrophobic poly-Leu and poly-Phe at 1 and 10 weight percent greatly increased the adsorption facility of DPPC and DPPC/PG mixtures, with maximum surface pressures (up to 49 mN/m) near the equilibrium limit for phospholipid systems. In oscillating bubble studies, 1% mixture of poly-Leu or poly-Phe with DPPC or 8:2 DPPC/PG lowered surface tension into the range (near 1 mN/m) associated with active lung surfactant. In contrast, mixtures of DPPC and DPPC/PG with the more hydrophilic peptides poly-Ser, poly-Lys and poly-Glu showed little or no enhancement of surface activity over the phospholipids alone. Mixtures of poly-Val and phospholipids did not combine well with the simple co-sonication procedure used, and also exhibited little improvement in surface activity. Taken together, these results suggest that dydrophobicity is an important determinant for interactions of proteins with lung surfactant phospholipids, and that significant biophysical activity effects are not limited to highly specific amino acid sequences of the surfactant apoproteins, SP-B and SP-C. Simple homoamino acid polymers may provide useful model systems for investigating the specificity and character of some of these interactions, as well as the effectiveness of protein- phospholipidcombination in synthetic surfactant mixtures.

Original languageEnglish (US)
Pages (from-to)157-164
Number of pages8
JournalChemistry and Physics of Lipids
Volume53
Issue number2-3
DOIs
StatePublished - 1990
Externally publishedYes

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1,2-Dipalmitoylphosphatidylcholine
Phospholipids
Lung
Phosphatidylglycerols
Peptides
Surface-Active Agents
Phenylalanine
Leucine
Apoproteins
Surface Tension
Valine
Apolipoproteins B
Serine
Adsorption
Lysine
Acids
Surface tension
Glutamic Acid
Pulmonary Surfactant-Associated Proteins
Amino Acids

Keywords

  • dipalmitoyl phosphatidylcholine
  • hydrophobic peptide
  • lipid-protein interactions
  • pulmonary surfactants
  • surface adsorption
  • surfactant apoproteins

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics

Cite this

Hydrophobic homopolymeric peptides enhance the biophysical activity of synthetic lung phospholipids. / Venkitaraman, A. R.; Hall, Stephen (Steve); Notter, R. H.

In: Chemistry and Physics of Lipids, Vol. 53, No. 2-3, 1990, p. 157-164.

Research output: Contribution to journalArticle

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abstract = "The effects of homopolymeric amino acids (molecular weight 2300 to 14,000) on the surface activity of dipalmitoyl phosphatidylcholine (DPPC) and DPPC/egg-phosphatidylglycerol (PG) were characterized by adsorption and dynamic surface tension lowering measurements at 37°C. Homopolyamino acids studied included polyl-leucine (poly-Leu) and poly-l-valine (poly-Val), since Leu and Val are known to be prominent in the structure of hydrophobic lung surfactant apoprotein SP-B and SP-C. In addition, several other homopolyamino acids with varying hydrophobicity index were also investigated, including poly-l-phenylalanine (poly-Phe), poly-l-serine (poly-Ser), poly-l-lysine (poly-Lys) and poly-l-glutamic acid (poly-Glu). Results showed that hydrophobic poly-Leu and poly-Phe at 1 and 10 weight percent greatly increased the adsorption facility of DPPC and DPPC/PG mixtures, with maximum surface pressures (up to 49 mN/m) near the equilibrium limit for phospholipid systems. In oscillating bubble studies, 1{\%} mixture of poly-Leu or poly-Phe with DPPC or 8:2 DPPC/PG lowered surface tension into the range (near 1 mN/m) associated with active lung surfactant. In contrast, mixtures of DPPC and DPPC/PG with the more hydrophilic peptides poly-Ser, poly-Lys and poly-Glu showed little or no enhancement of surface activity over the phospholipids alone. Mixtures of poly-Val and phospholipids did not combine well with the simple co-sonication procedure used, and also exhibited little improvement in surface activity. Taken together, these results suggest that dydrophobicity is an important determinant for interactions of proteins with lung surfactant phospholipids, and that significant biophysical activity effects are not limited to highly specific amino acid sequences of the surfactant apoproteins, SP-B and SP-C. Simple homoamino acid polymers may provide useful model systems for investigating the specificity and character of some of these interactions, as well as the effectiveness of protein- phospholipidcombination in synthetic surfactant mixtures.",
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N2 - The effects of homopolymeric amino acids (molecular weight 2300 to 14,000) on the surface activity of dipalmitoyl phosphatidylcholine (DPPC) and DPPC/egg-phosphatidylglycerol (PG) were characterized by adsorption and dynamic surface tension lowering measurements at 37°C. Homopolyamino acids studied included polyl-leucine (poly-Leu) and poly-l-valine (poly-Val), since Leu and Val are known to be prominent in the structure of hydrophobic lung surfactant apoprotein SP-B and SP-C. In addition, several other homopolyamino acids with varying hydrophobicity index were also investigated, including poly-l-phenylalanine (poly-Phe), poly-l-serine (poly-Ser), poly-l-lysine (poly-Lys) and poly-l-glutamic acid (poly-Glu). Results showed that hydrophobic poly-Leu and poly-Phe at 1 and 10 weight percent greatly increased the adsorption facility of DPPC and DPPC/PG mixtures, with maximum surface pressures (up to 49 mN/m) near the equilibrium limit for phospholipid systems. In oscillating bubble studies, 1% mixture of poly-Leu or poly-Phe with DPPC or 8:2 DPPC/PG lowered surface tension into the range (near 1 mN/m) associated with active lung surfactant. In contrast, mixtures of DPPC and DPPC/PG with the more hydrophilic peptides poly-Ser, poly-Lys and poly-Glu showed little or no enhancement of surface activity over the phospholipids alone. Mixtures of poly-Val and phospholipids did not combine well with the simple co-sonication procedure used, and also exhibited little improvement in surface activity. Taken together, these results suggest that dydrophobicity is an important determinant for interactions of proteins with lung surfactant phospholipids, and that significant biophysical activity effects are not limited to highly specific amino acid sequences of the surfactant apoproteins, SP-B and SP-C. Simple homoamino acid polymers may provide useful model systems for investigating the specificity and character of some of these interactions, as well as the effectiveness of protein- phospholipidcombination in synthetic surfactant mixtures.

AB - The effects of homopolymeric amino acids (molecular weight 2300 to 14,000) on the surface activity of dipalmitoyl phosphatidylcholine (DPPC) and DPPC/egg-phosphatidylglycerol (PG) were characterized by adsorption and dynamic surface tension lowering measurements at 37°C. Homopolyamino acids studied included polyl-leucine (poly-Leu) and poly-l-valine (poly-Val), since Leu and Val are known to be prominent in the structure of hydrophobic lung surfactant apoprotein SP-B and SP-C. In addition, several other homopolyamino acids with varying hydrophobicity index were also investigated, including poly-l-phenylalanine (poly-Phe), poly-l-serine (poly-Ser), poly-l-lysine (poly-Lys) and poly-l-glutamic acid (poly-Glu). Results showed that hydrophobic poly-Leu and poly-Phe at 1 and 10 weight percent greatly increased the adsorption facility of DPPC and DPPC/PG mixtures, with maximum surface pressures (up to 49 mN/m) near the equilibrium limit for phospholipid systems. In oscillating bubble studies, 1% mixture of poly-Leu or poly-Phe with DPPC or 8:2 DPPC/PG lowered surface tension into the range (near 1 mN/m) associated with active lung surfactant. In contrast, mixtures of DPPC and DPPC/PG with the more hydrophilic peptides poly-Ser, poly-Lys and poly-Glu showed little or no enhancement of surface activity over the phospholipids alone. Mixtures of poly-Val and phospholipids did not combine well with the simple co-sonication procedure used, and also exhibited little improvement in surface activity. Taken together, these results suggest that dydrophobicity is an important determinant for interactions of proteins with lung surfactant phospholipids, and that significant biophysical activity effects are not limited to highly specific amino acid sequences of the surfactant apoproteins, SP-B and SP-C. Simple homoamino acid polymers may provide useful model systems for investigating the specificity and character of some of these interactions, as well as the effectiveness of protein- phospholipidcombination in synthetic surfactant mixtures.

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