Sodium dodecyl sulfate-disc gel electrophoresis patterns of bovine lung surfactant.

Bovine lung surfactant material, isolated by three steps of centrifugation from lung washings, had a phospholipid: protein ration of 4.98+/-S.D. 0.62 mumol/mg. Sucrose continuous density gradient centrifugation showed only one visible band at a density of 1.081 g/ml. Sodium dodecyl sulfate-disc gel electrophoresis patterns of the apoprotein extracted from this material revealed that the main component (70-80%) of the protein subunits of bovine lung surfactant material has a molecular weight of 36 000. It was suggested that the apoprotein of bovine lung surfactant material exists as a combination of a few protein subunits, most of which have a molecular weight of 36 000.