Jordanova Albena, Georgiev Georgi As, Alexandrov Svobodan, Todorov Roumen, Lalchev Zdravko
Department of Lipid-Protein Interactions, Institute of Biophysics, Bulgarian Academy of Sciences, 1113, Sofia, Bulgaria.
Eur Biophys J. 2009 Apr;38(4):369-79. doi: 10.1007/s00249-008-0380-2. Epub 2008 Nov 1.
In the current work we study with monolayer tensiometry and Brewster angle microscopy (BAM) the surface properties of Dipalmitoleoylphosphatidylethanolamine (DPoPE) films at the air/water interface in presence and absence of specific surfactant protein C (SP-C). DPoPE is used, as it readily forms both lamellar (L(alpha)) and non-lamellar inverted hexagonal (H(II)) phases and appears as a suitable model phospholipid for probing the interfacial properties of distinct lipid phases. At pure air/water interface L(alpha) shows faster adsorption and better surface disintegration than H(II) phase. The interaction of DPoPE molecules with SP-C (predeposited at the interface) results in equalizing of the interfacial disintegration of the both phases (reaching approximately the same equilibrium surface tension) although the adsorption kinetics of the lamellar phase remains much faster. Monolayer compression/decompression cycling revealed that the effect of SP-C on dynamic surface tensions (gamma (max) and gamma (min)) of mixed films is remarkably different for the two phases. If gamma (max) for L(alpha) decreased from the first to the third cycle, the opposite effect is registered for H(II) where gamma (max) increases during cycling. Also the significant decrease of gamma (min) for L(alpha) in SP-C presence is not observed for H(II) phase. BAM studies reveal the formation of more uniform and homogeneously packed DPoPE monolayers in the presence of SP-C.
在当前工作中，我们使用单层张力测定法和布鲁斯特角显微镜（BAM）研究了在有和没有特定表面活性蛋白C（SP-C）存在的情况下，二棕榈油酰磷脂酰乙醇胺（DPoPE）膜在空气/水界面的表面性质。使用DPoPE是因为它很容易形成层状（L(α)）和非层状反相六角形（H(II)）相，并且似乎是用于探测不同脂质相界面性质的合适模型磷脂。在纯空气/水界面，L(α)相显示出比H(II)相更快的吸附和更好的表面崩解。DPoPE分子与（预先沉积在界面处的）SP-C的相互作用导致两相的界面崩解达到平衡（达到大致相同的平衡表面张力），尽管层状相的吸附动力学仍然快得多。单层压缩/解压循环表明，对于这两个相，SP-C对混合膜动态表面张力（γ(max)和γ(min)）的影响显著不同。如果L(α)相的γ(max)从第一个循环到第三个循环下降，那么对于H(II)相则观察到相反的效果，即γ(max)在循环过程中增加。而且，在存在SP-C的情况下，L(α)相的γ(min)显著降低，而H(II)相则未观察到这种情况。BAM研究表明，在存在SP-C的情况下，会形成更均匀且堆积更紧密的DPoPE单层膜。
