Effect of the hydrophobic surfactant proteins on the surface activity of spread films in the captive bubble surfactometer.
The main function of pulmonary surfactant, a mixture of lipids and proteins, is to reduce the surface tension at the air/liquid interface of the lung. The hydrophobic surfactant proteins SP-B and SP-C are required for this process. When testing their activity in spread films in a captive bubble surfactometer, both SP-B and SP-C showed concentration dependence for lipid insertion as well as for lipid film refinement. Higher activity in DPPC refinement of the monolayer was observed for SP-B compared with SP-C. Further differences between both proteins were found, when subphase phospholipid vesicles, able to create a monolayer-attached lipid reservoir, were omitted. SP-C containing monolayers showed gradually increasing minimum surface tensions upon cycling, indicating that a lipid reservoir is required to prevent loss of material from the monolayer. Despite reversible cycling dynamics, SP-B containing monolayers failed to reach near-zero minimum surface tensions, indicating that the reservoir is required for stable films.
Veldhuizen
E J
EJ
Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Institute of Biomembranes and Graduate School of Animal Health, Utrecht University, P.O. Box 80176, 3508 TD, Utrecht, The Netherlands.
Diemel
R V
RV
Putz
G
G
van Golde
L M
LM
Batenburg
J J
JJ
Haagsman
H P
HP
D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D004548:Elasticity; D008081:Liposomes / Q000737:chemistry*; D010715:Phosphatidylglycerols / Q000737:chemistry; D011510:Proteolipids / Q000737:chemistry*; D011663:Pulmonary Surfactants / Q000737:chemistry*; D013500:Surface Tension
D008081:Liposomes; D010715:Phosphatidylglycerols; D011510:Proteolipids; D011663:Pulmonary Surfactants; D015060:1,2-Dipalmitoylphosphatidylcholine