Interfacial adsorption of simple lipid mixtures combined with hydrophobic surfactant protein from pig lung

Abstract

Hydrophobic pulmonary surfactant protein enriched in SP-C has been mixed in amounts up to 10% by weight with various phospholipids. The lipids used were dipalmitoyl phosphatidylcholine (DPPC), or DPPC plus unsaturated phosphatidylglycerol (PG), or phosphatidylinositol (PI) in molar ratios of 9:1 and 7:3. The protein enhanced the rate and extent of adsorption of each lipid preparation into the air-water interface, and its respreading after compression on a surface balance. Maximum surface pressures attained on compression of monolayers of mixtures of lipids were slightly higher in the presence of protein. The effects on rate and extent of adsorption were proportional to the amount of protein present. Mixtures containing 30 mol% PG or PI adsorbed more readily into the interface than those containing 10% acidic lipid or DPPC alone. Mixtures containing 30% PI were slightly more rapidly adsorbed than those containing 30% PG. The results suggest that mixtures of DPPC with either acidic lipid in the presence of surfactant protein could be effective in artificial surfactants.

High-throughput evaluation of pulmonary surfactant adsorption and surface film formation

“…Interfacial adsorption of surfactant samples was also followed on a Teflon-made King-Clements-type of surface balance (22), specially designed by Nima (Coventry, UK) (29). The total volume of subphase was 1.5 ml, thermostatized at the indicated temperature, and continuously stirred with a 2 mm-long magnetic bar.…”

“…Such surface properties can be evaluated in traditional surface balances, in the so-called pulsating bubble surfactometer (PBS), or in the more sophisticated captive bubble surfactometer (CBS). Surfactant adsorption as measured in miniaturized King-Clements devices (21,22) or the compression isotherms of surfactant as obtained in Langmuir balances (23) provide detailed measurements that can be correlated with potential configurations and interactions of lipid and protein molecules as organized at the air-liquid interface. The technical constraints of these experiments, however, are usually far from relevant physiological conditions regarding temperature, appropriate surfactant concentrations, and surface cycling.…”

Surfactant Protein B: Structure and Function

“…SP-B clearly enhances the rate of adsorption of phospholipids from an aqueous subphase to an air-water interface [3,5,31,32]. Many of the membrane actions of SP-B discussed already may be relevant to this step as the addition of lipid to a preformed monolayer probably involves the fusion of subphase bilayer structures to the surface monolayer [24,33] (fig.…”

Selective Labeling of Pulmonary Surfactant Protein SP-C in Organic Solution

“…To compare biophysical activity of native and dansyl-labeled SP-C, 300 nmol of a DPPC multilamellar suspension, prepared in the absence or in the presence of 10% (w/w) of the respective protein, was dispersed with continuous stirring in 6 mL of a hypophase Hepes 50 mM, pH 7, containing 150 mM NaCl and 5 mM CaCl 2 . Interfacial adsorption of the samples was monitored over 45 min by measuring the changes in surface pressure with a Wilhelmy plate connected to a pressure transducer (29,30).…”