title: Effect of calcium on phospholipid interaction with pulmonary surfactant protein C.
abstract: Porcine pulmonary surfactant-associated protein SP-C was incorporated into bilayers of chain-perdeuterated dipalmitoylphosphatidylglycerol (DPPG-d62) and chain-perdeuterated dipalmitoyl-phosphatidylcholine (DPPC-d62) and into bilayers containing 70 mol% dipalmitoyl-phosphatidylcholine (DPPC) and 30 mol% DPPG-d62 or 70 mol% DPPC-d62 and 30 mol% dipalmitoylphosphatidylglycerol (DPPG). The effect of SP-C on the phase behavior, lipid chain order, and dynamics in these bilayers was examined by using deuterium nuclear magnetic resonance. SP-C was found to have a similar effect on the chain order and phase behavior of DPPC-d62 and DPPG-d62 in bilayers with a single lipid component. In gel phase DPPC/DPPG (7:3) bilayers with one or the other lipid component chain-perdeuterated, SP-C was found to affect first spectral moment more strongly for DPPG-d62 than for DPPC-d62. This may indicate that SP-C induced a nonrandom lateral distribution in the mixed lipid bilayer. SP-C was also found to influence motions responsible for deuteron transverse relaxation in both the gel and liquid crystalline phases. The presence of 5 mM Ca2+ in the aqueous phase substantially altered the effect of SP-C on transverse relaxation in the bilayer.
authors.affiliation: Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, Canada.
authors.forename: A S
authors.initials: AS
authors.lastname: Dico
authors.forename: S
authors.initials: S
authors.lastname: Taneva
authors.forename: M R
authors.initials: MR
authors.lastname: Morrow
authors.forename: K M
authors.initials: KM
authors.lastname: Keough
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D003903:Deuterium; D005782:Gels; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D010715:Phosphatidylglycerols / Q000737:chemistry / Q000378:metabolism*; D010743:Phospholipids / Q000737:chemistry* / Q000378:metabolism*; D011510:Proteolipids / Q000378:metabolism* / Q000494:pharmacology; D011663:Pulmonary Surfactants / Q000378:metabolism* / Q000494:pharmacology; D013552:Swine; D013696:Temperature
chemical_list: D005782:Gels; D008051:Lipid Bilayers; D010715:Phosphatidylglycerols; D010743:Phospholipids; D011510:Proteolipids; D011663:Pulmonary Surfactants; D015060:1,2-Dipalmitoylphosphatidylcholine; D003903:Deuterium; D002118:Calcium; C030345:1,2-dipalmitoylphosphatidylglycerol