出版社：American Society for Biochemistry and Molecular Biology
摘要：This study shows that the hydrophobic lung surfactant proteins (SP)-B and SP-C are not synergistic in enhancing functionally relevant surface behaviors in films and dispersions with phospholipids, and that SP-B is more effective than SP-C in facilitating surface activity. Purified bovine SP-B, SP. C, or SP-B/C (1/1 by wt) were combined with chroma tographically purified calf lung surfactant phospholipids (PPL), or with dipalmitoyl phosphatidylcholine (DPPC) or complex phospholipid mixtures containing 75% or 50% DPPC (75% SPL or 50% SPL). Adsorption was consistently better in corresponding mixtures of phospholipids plus SP-B versus SP-C, but was not improved further by substitution of SP-B/C for SP-B. Interfacial films of DPPC or SPL plus 1.3% SP-B or 1.3% SP-C had improved respreading compared to phospholipids alone (Wilhelmy balance, 23 degrees C and 37 degrees C), but substitution of mixed SP-B/C for either pure apoprotein did not increase respreading further. Surface-excess films of phospholipids plus SP-B had higher maximum surface pressures, or maintained a high maximum pressure through more consecutive compressions, than corresponding films with SP-C. Dispersions of phospholipids plus 1.3% SP-B or mixed (1/1) SP-B/C (2.6%) rapidly lowered surface tension to
