Analysis of lung surfactant model systems with time-of-flight secondary ion mass spectrometry.
An often-used model lung surfactant containing dipalmitoylphosphatidylcholine (DPPC), dipalmitoylphosphatidylglycerol (DPPG), and the surfactant protein C (SP-C) was analyzed as Langmuir-Blodgett film by spatially resolved time-of-flight secondary ion mass spectrometry (TOF-SIMS) to directly visualize the formation and composition of domains. Binary lipid and lipid/SP-C systems were probed for comparison. TOF-SIMS spectra revealed positive secondary ions (SI) characteristic for DPPC and SP-C, but not for DPPG. SI mapping results in images with domain structures in DPPC/DPPG and DPPG/SP-C, but not in DPPC/SP-C films. We are able to distinguish between the fluid and condensed areas probably due to a matrix effect. These findings correspond with other imaging techniques, fluorescence light microscopy (FLM), scanning force microscopy (SFM), and silver decoration. The ternary mixture DPPC/DPPG/SP-C transferred from the collapse region exhibited SP-C-rich domains surrounding pure lipid areas. The results obtained are in full accordance with our earlier SFM picture of layered protrusions that serve as a compressed reservoir for surfactant material during expansion. Our study demonstrates once more that SP-C plays a unique role in the respiration process.
Bourdos
N
N
Institut für Biochemie, Westfälische Wilhelms-Universität, D-48149 Münster, Germany.
Kollmer
F
F
Benninghoven
A
A
Ross
M
M
Sieber
M
M
Galla
H J
HJ
D015060:1,2-Dipalmitoylphosphatidylcholine / Q000032:analysis / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry; D008567:Membranes, Artificial; D008956:Models, Chemical; D010715:Phosphatidylglycerols / Q000032:analysis / Q000737:chemistry; D011312:Pressure; D011510:Proteolipids / Q000032:analysis / Q000737:chemistry; D011663:Pulmonary Surfactants / Q000032:analysis* / Q000737:chemistry*; D018629:Spectrometry, Mass, Secondary Ion; D013499:Surface Properties; D013500:Surface Tension
D008051:Lipid Bilayers; D008567:Membranes, Artificial; D010715:Phosphatidylglycerols; D011510:Proteolipids; D011663:Pulmonary Surfactants; D015060:1,2-Dipalmitoylphosphatidylcholine; C030345:1,2-dipalmitoylphosphatidylglycerol