Physicochemical studies on goat pulmonary surfactant

Area of Science:

• Biochemistry
• Biophysics
• Materials Science

Background:

• Pulmonary surfactant is crucial for lung function, reducing surface tension.
• Goat pulmonary surfactant (GPS) composition differs from other mammals.
• Understanding GPS composition is key to its functionality.

Purpose of the Study:

• To isolate and characterize the large aggregate (LA) fraction of goat pulmonary surfactant (GPS).
• To determine the biochemical composition of goat lung surfactant extract (GLSE).
• To analyze the structural and functional properties of GLSE films.

Main Methods:

• Isolation and biochemical estimation of phospholipid (PL), cholesterol (CHOL), and protein in GLSE.
• Electrospray Ionization Mass Spectrometry (ESIMS) for phospholipid species identification.
• Langmuir surface balance for surface pressure (π)-area (A) measurements and atomic force microscopy (AFM) for film imaging.

Main Results:

• GLSE comprised approximately 83% PL, 0.6% CHOL, and 16% protein.
• CHOL content was lower and protein content higher than in other mammalian surfactants.
• ESIMS identified dipalmitoylphosphatidylcholine (DPPC) as the major PL species.
• Langmuir-Blodgett (LB) films exhibited high surface pressure (π ≈ 65 mN m⁻¹) and significant hysteresis.
• AFM revealed DPPC-enriched domains (≈2.5 μm) that changed shape under compression.

Conclusions:

• Goat pulmonary surfactant (GPS) exhibits unique biochemical composition (low CHOL, high protein).
• The structure and functionality of GLSE films are influenced by protein and cholesterol content.
• DPPC is the primary phospholipid, contributing to the surfactant's biophysical properties.