EFFECT OF A BOVINE LUNG SURFACTANT PROTEIN ISOLATE (SP-B C) ON EGG PHOSPHATIDYLGLYCEROL ACYL-CHAIN ORDER IN A LIPID MIXTURE WITH DIPALMITOYLPHOSPHATIDYLCHOLINE AND PALMITIC ACID/

Dynamic surface tension measurements of films of a d(62) idylcholine:L -alpha-phosphatidyl-DL-glycerol:d(31) palmitic acid (d(62)-DPPC:EggPG: d(31)-PA) lipid matrix in the presence of a bovine pulmonary surfactan t protein isolate (SP-B/G) demonstrate the improved surface activity o ver that of the lipids alone. Thus, significant interaction of the pro teins with the lipid matrix is demonstrated. The effect of SP-B/C on t he acyl chain order of the negatively charged EggPG within a d(62)-DPP C:EggPG:d(31)-PA lipid matrix in D2O saline was investigated in therma l perturbation Fourier transform IR spectroscopic studies. The EggPG t hermotropic phase behavior was determined independently of the other l ipid components with perdeuterated lipids and D2O. The data demonstrat e the high degree of EggPG acyl chain disorder in the absence of the p rotein isolate. A broad transition occurs between 30 and 40 degrees C. The addition of the protein isolate did not alter the acyl chain orde r at 0.281 and 1.46 mg/ml of protein. However, alterations in the lipi d carbonyl vibrational mode were observed.