Taneva S G, Keough K M
Department of Biochemistry, Memorial University of Newfoundland, St. John's, Canada.
Biochim Biophys Acta. 1995 May 24;1236(1):185-95. doi: 10.1016/0005-2736(95)00046-6.
Spread monolayers containing hydrophobic pulmonary surfactant protein, SP-B or SP-C, or SP-B/SP-C (2:1, w/w), alone or mixed with dipalmitoylphosphatidylcholine (DPPC) or dipalmitoylphosphatidylglycerol (DPPG), were formed on saline subphases containing calcium ions. Surface pressure-area characteristics of the films of the proteins were not affected by the presence of Ca2+ in the subphase. Calcium ions did not alter the surface properties of the binary and ternary films of DPPC plus either SP-B, or SP-C, or SP-B/SP-C (2:1, w/w). Surface pressure-area isotherms for the spread films of DPPG plus hydrophobic surfactant protein were Ca(2+)-dependent. The exclusion pressures of SP-B, SP-C and SP-B/SP-C (2:1, w/w) from protein-DPPG films in the presence of calcium were lower than the exclusion pressures in the absence of Ca2+. The divalent cation appeared to suppress the ability of SP-C and SP-B/SP-C (2:1, w/w) to remove phospholipid during squeeze-out from their mixed films with DPPG. The effects of Ca2+ on the monolayers of DPPG plus hydrophobic surfactant proteins were consistent with calcium producing diminished lipid-protein interactions, possibly resulting from Ca(2+)-induced changes in the ionization state and molecular packing of DPPG.
在含有钙离子的盐水亚相中形成了包含疏水性肺表面活性蛋白SP - B或SP - C或SP - B/SP - C（2:1，w/w）的铺展单层，这些单层单独存在或与二棕榈酰磷脂酰胆碱（DPPC）或二棕榈酰磷脂酰甘油（DPPG）混合。蛋白质薄膜的表面压力 - 面积特性不受亚相中Ca2+存在的影响。钙离子不会改变DPPC与SP - B、或SP - C、或SP - B/SP - C（2:1，w/w）形成的二元和三元薄膜的表面性质。DPPG与疏水性表面活性蛋白的铺展薄膜的表面压力 - 面积等温线取决于Ca(2+)。在有钙存在的情况下，SP - B、SP - C和SP - B/SP - C（2:1，w/w）从蛋白质 - DPPG薄膜中的排出压力低于无Ca2+时的排出压力。二价阳离子似乎抑制了SP - C和SP - B/SP - C（2:1，w/w）在与DPPG的混合薄膜挤出过程中去除磷脂的能力。Ca2+对DPPG与疏水性表面活性蛋白单层的影响与钙导致脂质 - 蛋白质相互作用减弱一致，这可能是由于Ca(2+)诱导DPPG的电离状态和分子堆积发生变化所致。
