Yu S H, Possmayer F
Department of Obstetrics and Gynaecology, University of Western Ontario, London, Canada.
Biochim Biophys Acta. 1992 Jun 5;1126(1):26-34. doi: 10.1016/0005-2760(92)90212-e.
The pulsating bubble technique was used to study the surface activity of binary phospholipid mixtures containing dipalmitoyl-phosphatidylcholine (DPPC) and an unsaturated acidic phospholipid such as egg phosphatidylglycerol (egg PG), 1-palmitoyl-2-oleoyl-PG (POPG) or egg phosphatidic acid (egg PA) in the presence of surfactant-associated protein B (SP-B) and calcium. The relative surface activities were DPPC/egg PG/SP-B (7:3:1%) greater than DPPC/POPG/SP-B (7:3:1%) greater than DPPC/egg PA/SP-B (7:3:1%). The Wilhelmy surface plate technique was utilized to investigate the interaction between pure SP-B in the bulk phase (0.9% NaCl/1.5 mM CaCl2) and preformed DPPC or phosphatidylglycerol (PG) monolayers. Although SP-B injected into the bulk phase reduces the surface tension of a clean surface, no evidence was obtained for the insertion of SP-B into surface monolayers at equilibrium surface tension. Surface radioactivity measurements and the Wilhelmy surface plate technique were also used to study the potential interactions between liposomes of DPPC/POPG (7:3) with or without SP-B and surface monolayers of [14C]DPPC or [14C]POPG. No exchange of phosphatidylcholine (PC) or PG was found between the monolayer and liposomes. We also compared the adsorption of pure POPG or 1-palmitoyl-2-oleoyl- phosphatidylcholine (POPC) and binary mixed liposomes with DPPC in the presence or absence of SP-B and calcium. DPPC/POPG/SP-B (7:3:1%) was found to be more surface active than pure POPG plus 1% SP-B in the presence of calcium. Injection of SP-B into the bulk phase promoted the adsorption of DPPC/POPG liposomes to a greater extent than POPG liposomes. The enhanced adsorption was dependent on the presence of calcium. In contrast to PG, DPPC/POPC/SP-B (7:3:1%) was less surface active than pure POPC plus 1% SP-B either in the presence or absence of calcium. Our findings suggested that the molecular composition and organization of mixed monolayers play an important role in the surface activity of the surfactant.
采用脉动气泡技术研究了在表面活性蛋白B（SP - B）和钙存在的情况下，含有二棕榈酰磷脂酰胆碱（DPPC）和不饱和酸性磷脂（如鸡蛋磷脂酰甘油（鸡蛋PG）、1 - 棕榈酰 - 2 - 油酰 - PG（POPG）或鸡蛋磷脂酸（鸡蛋PA））的二元磷脂混合物的表面活性。相对表面活性为DPPC/鸡蛋PG/SP - B（7:3:1%）大于DPPC/POPG/SP - B（7:3:1%）大于DPPC/鸡蛋PA/SP - B（7:3:1%）。利用Wilhelmy表面板技术研究了本体相（0.9% NaCl/1.5 mM CaCl₂）中的纯SP - B与预先形成的DPPC或磷脂酰甘油（PG）单层之间的相互作用。尽管注入本体相的SP - B降低了清洁表面的表面张力，但在平衡表面张力下未获得SP - B插入表面单层的证据。表面放射性测量和Wilhelmy表面板技术还用于研究有或没有SP - B的DPPC/POPG（7:3）脂质体与[¹⁴C]DPPC或[¹⁴C]POPG表面单层之间的潜在相互作用。在单层和脂质体之间未发现磷脂酰胆碱（PC）或PG的交换。我们还比较了在有或没有SP - B和钙的情况下，纯POPG或1 - 棕榈酰 - 2 - 油酰磷脂酰胆碱（POPC）以及与DPPC的二元混合脂质体的吸附情况。发现在有钙的情况下，DPPC/POPG/SP - B（7:3:1%）比纯POPG加1% SP - B更具表面活性。将SP - B注入本体相比POPG脂质体在更大程度上促进了DPPC/POPG脂质体的吸附。增强的吸附取决于钙的存在。与PG相反，无论在有或没有钙的情况下，DPPC/POPC/SP - B（7:3:1%）都比纯POPC加1% SP - B的表面活性低。我们的研究结果表明，混合单层的分子组成和组织在表面活性剂的表面活性中起重要作用。
