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.
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.
E J
EJ
Veldhuizen
R V
RV
Diemel
G
G
Putz
L M
LM
van Golde
J J
JJ
Batenburg
H P
HP
Haagsman
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