The model of the action mechanism of SP-C in the lung surfactant monolayers.
The action mechanism of surfactant protein C (SP-C) in the lung surfactant monolayers is studied. On the basis of the SP-C molecular structure, a detailed interaction model is developed to describe the interaction of phospholipids/SP-C in the lung surfactant monolayers. It is supposed that: (1) in an alveolus monolayer, SP-C molecules are surrounded by phosphatidylglycerol (PG). When the monolayer is compressed, SP-C molecules can promote PG molecules to be squeezed out; (2) during compressing of the monolayer, unsaturated-PG molecules form a collapse pit firstly when liquid-expanded state (LE) components achieve the collapse pressure. Then, SP-C's alpha-helix is attracted by the collapse pit and both alpha-helix and PG molecules are squeezed out speedily. Finally, the squeezed-out matters can form a lipid-protein aggregation in the subphase. The lipid-protein aggregation, in the centre of which, there is the hydrophobic alpha-helix section surrounded by PG molecules; (3) during the monolayer expanding, because of the increasing of the monolayer's surface tension, the structure of the lipid-protein aggregation is disturbed and reinserts into the surface of the monolayer rapidly. On the basis of analyzing the energies change of the squeeze-out process, a mathematical model is obtained to calculate the squeezed-out number of DPPG molecules when a SP-C molecule squeezes out in a monolayer. According to the model, it is concluded that SP-C has the capability to promote the squeeze-out and the reinsertion of most of PG component in an alveolus monolayer, the prediction data agree well with the experimental data.
Li
Dan
D
Chemical Engineering Institute, East China University of Science and Technology, Shanghai 200237, China.
Zeng
Zuoxiang
Z
Xue
Weilan
W
Yao
Yali
Y
D001673:Biodegradation, Environmental; D018914:Cells, Immobilized; D003470:Culture Media; D009281:Naphthalenes / Q000737:chemistry / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000378:metabolism*; D014465:Ultrasonics; D014865:Waste Disposal, Fluid
D003470:Culture Media; D009281:Naphthalenes; C031721:naphthalene