Nilsson G, Gustafsson M, Vandenbussche G, Veldhuizen E, Griffiths W J, Sjövall J, Haagsman H P, Ruysschaert J M, Robertson B, Curstedt T, Johansson J
Department of Clinical Chemistry, Karolinska Institutet at Karolinska and Danderyd Hospital, Sweden.
Eur J Biochem. 1998 Jul 1;255(1):116-24. doi: 10.1046/j.1432-1327.1998.2550116.x.
Pulmonary surfactant contains two hydrophobic proteins, SP-B and SP-C. With the aim of identifying synthetic SP-B and SP-C substitutes for replacement therapy of respiratory distress syndromes, we have studied two transmembrane peptides and two amphipathic peptides that are located in the plane of a phospholipid bilayer. One amphipathic peptide was designed by changing the amino acid sequence, but not the composition or size, of the 21-residue peptide KL4. This peptide, designated KL(2,3) from its spacing of nonpolar and polar residues, exhibited similar alpha-helical content as KL4 but was oriented along a phospholipid bilayer plane, in contrast to the transmembrane orientation of KL4 in the same environment. The second amphipathic peptide analyzed was succinyl-LLEKLLEWLK-amide (WMAP10). KL4 more efficiently accelerated the spreading of a mixture of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (Pam2GroPCho)/phosphatidylglycerol (PtdGro)/palmitic acid (PamOH), 68:22:9 (by mass), at an air/water interface than did any of the amphipathic peptides. Similarly, KL4, but not KL(2,3), when present in an interfacial monolayer composed of Pam2GroPCho/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol, 7:3 (by mass), increased lipid insertion from subphase vesicles. An SP-C analogue, SP-C(Leu), with all helical valyl residues in native SP-C replaced with Leu and the palmitoylcysteines at positions 5 and 6 replaced with Ser, but otherwise with essentially the same primary structure as the native peptide, was analyzed. SP-C(Leu) exhibited similar alpha-helical content as native SP-C and a transmembrane orientation and, in contrast to poly-valyl-containing synthetic peptides, it folds into a helical conformation after acid-induced denaturation. SP-C(Leu) accelerated the spreading of Pam2GroPCho/PtdGro/PamOH, 68:22:9 (by mass), almost identically to native SP-C, and lowered the surface tension during rapid cyclic film compressions in a pulsating bubble surfactometer to near zero and 43 mN/m at minimum and maximum bubble size, respectively. Airway instillation of 2% (by mass) SP-C(Leu) combined with Pam2GroPCho/PtdGro/PamOH in preterm rabbit fetuses improved dynamic lung compliance by about 30% compared with untreated controls.
肺表面活性物质包含两种疏水蛋白，即表面活性蛋白B（SP - B）和表面活性蛋白C（SP - C）。为了鉴定用于呼吸窘迫综合征替代疗法的合成SP - B和SP - C替代物，我们研究了位于磷脂双分子层平面内的两种跨膜肽和两种两亲性肽。一种两亲性肽是通过改变21个氨基酸残基的肽KL4的氨基酸序列而设计的，但不改变其组成或大小。根据其非极性和极性残基的间距，该肽被命名为KL(2,3)，与KL4在相同环境中的跨膜取向相反，它在磷脂双分子层平面内呈取向排列，且与KL4具有相似的α - 螺旋含量。分析的第二种两亲性肽是琥珀酰 - LLEKLLEWLK - 酰胺（WMAP10）。在空气/水界面，KL4比任何一种两亲性肽都更有效地加速了1,2 - 二棕榈酰 - sn - 甘油 - 3 - 磷酸胆碱（Pam2GroPCho）/磷脂酰甘油（PtdGro）/棕榈酸（PamOH）质量比为68:22:9的混合物的铺展。同样，当存在于由Pam2GroPCho/1 - 棕榈酰 - 2 - 油酰 - sn - 甘油 - 3 - 磷酸甘油质量比为7:3组成的界面单层中时，KL4而非KL(2,3)增加了亚相囊泡中的脂质插入。分析了一种SP - C类似物SP - C(Leu)，其天然SP - C中所有螺旋缬氨酸残基被亮氨酸取代，5和6位的棕榈酰半胱氨酸被丝氨酸取代，但一级结构与天然肽基本相同。SP - C(Leu)与天然SP - C具有相似的α - 螺旋含量和跨膜取向，并且与含多个缬氨酸的合成肽不同，它在酸诱导变性后折叠成螺旋构象。SP - C(Leu)加速Pam2GroPCho/PtdGro/PamOH质量比为68:22:9的混合物铺展的效果几乎与天然SP - C相同，并且在脉动气泡表面张力仪中快速循环薄膜压缩过程中，分别将最小和最大气泡尺寸时的表面张力降低至接近零和43 mN/m。与未处理的对照组相比，在早产兔胎儿气道内滴注2%（质量分数）的SP - C(Leu)与Pam2GroPCho/PtdGro/PamOH的混合物可使动态肺顺应性提高约30%。
