Physical and Chemical Characterization of Pig Lung Surfactant Lipoprotein

Surfactant has been prepared by ultracentrifugation and density gradient centrifugation from pig lung lavage. The product is a lipoprotein, free of contamination by serum proteins, and containing 4 mg of phospholipid per milligram of protein. The lipid portion is 60% dipalmitoyl-lecithin plus small amounts of other phospholipids. The surfactant exhibits ultraviolet fluorescence. Excitation at 260±10 mμ gives a single emission maximum at 320±10 mμ. Anilinonaphthalene sulfonate binds to surfactant and gives an enhanced fluorescence peak at 465±10 mμ when excited at 375 ± 10 mμ. Mammalian lungs are lined by a surface active material which may help to prevent alveolar collapse at small lung volumes. Reduced quantities of this material are associated with the lung collapse observed in hyaline membrane disease.1Although the surface active properties of alveolar wash can be duplicated by dipalmitoyl-lecithin alone,2it does not necessarily follow that pure dipalmitoyl-lecithin lines the alveolar surface. Indeed,