Molecular Architecture of a Self-Assembled Bio-Interface: Lung Surfactant

摘要

Lung surfactant underlines the air-alveolar interface with various self-assembled structures and mono-molecular flims. These structures called lamellar bodies, and tubular myelin are assembled at the lung interface, by unclear biophysical interaction of surfactant, lipids and proteins. The flims reduce the surface tension of the lung air-water interface and prevent alveolar collapse at end expiration. This article suggests mechanisms by which the surface tension reduction is achieved, and reviews some current ideas about lung surfactant film dynamics. The films are formed by physical transformation and self-assembly, and the subphase material feeds the interface with a specific surfactant component dipalmitoylphosphatidylcholine (DPPC). Flims of extracted pulmonary surfactants from rat and bovine lungs were studied using structural and chemical methods. The chemical composition, structural features and the molecular arrangements of surfactants in Langmuir-Blodgett flims were studied using atomic force and fluorescence microscopy, and mass spectrometry. The flims underwent a two dimensional phase transition, and their molecular arrangements were altered during the transition. This process in relation to previously published information on surfactant and phospholipid films is discussed in this review. The investigations suggest self assembly, ordering in two-dimensions, and compaction of the films by a surface pressure induced phase transition, occurring at the lung air-water interface.