title: Hydrophobic homopolymeric peptides enhance the biophysical activity of synthetic lung phospholipids.
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 degrees C. Homopolyamino acids studied included poly-L-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.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Pediatrics, University of Rochester, New York 14642.
authors.forename: A R
authors.initials: AR
authors.lastname: Venkitaraman
authors.forename: S B
authors.initials: SB
authors.lastname: Hall
authors.forename: R H
authors.initials: RH
authors.lastname: Notter
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine; D000327:Adsorption; D000596:Amino Acids; D055592:Biophysical Phenomena; D001703:Biophysics; D008168:Lung / Q000378:metabolism; D008954:Models, Biological; D010455:Peptides; D010715:Phosphatidylglycerols; D011663:Pulmonary Surfactants / Q000138:chemical synthesis; D013500:Surface Tension
chemical_list: D000596:Amino Acids; D010455:Peptides; D010715:Phosphatidylglycerols; D011663:Pulmonary Surfactants; D015060:1,2-Dipalmitoylphosphatidylcholine