Department of Biochemistry, Tulane University School of Medicine, New Orleans, Louisiana, USA.
Biophys J. 2011 Aug 17;101(4):828-36. doi: 10.1016/j.bpj.2011.06.059.
Here we test the hypothesis that membrane-spanning β-sheets can exhibit structural plasticity in membranes due to their ability to shift hydrogen-bonding patterns. Transmembrane β-sheet forming peptides of the sequence AcWL(n), where n = 5, 6, or 7, which range from 21 to 27 Å in maximum length, were incorporated into bilayers made of phosphatidylcholine lipids with saturated acyl chains containing 14, 16, or 18 carbons, which are 36-50 Å in thickness. The effect of the peptide β-sheets on fluid- and gel-phase bilayers were studied with differential scanning calorimetry and circular dichroism spectroscopy. We show that AcWL₅ forms a stable, peptide-rich gel phase in all three lipids. The whole family of AcWL(n) peptides appears to form similarly stable, nonmembrane-disrupting β-sheets in all bilayer phases and thicknesses. Bilayers containing up to 20 mol % peptide, which is the maximum concentration tested, formed gel phases with melting temperatures that were equal to, or slightly higher than, the pure lipid transitions. Given the range of peptide lengths and bilayer thicknesses tested, these experiments show that the AcWL(n) family of membrane-inserted β-sheets exhibit remarkable structural plasticity in membranes.
在这里，我们检验了一个假设，即由于能够改变氢键模式，膜跨β-折叠在膜中可以表现出结构可塑性。我们将序列为 AcWL(n)的跨膜β-折叠形成肽（其中 n = 5、6 或 7）掺入到由具有饱和酰基链的磷脂脂质制成的双层中，这些酰基链含有 14、16 或 18 个碳原子，厚度为 36-50 Å。我们使用差示扫描量热法和圆二色性光谱研究了肽β-折叠对流体相和凝胶相双层的影响。我们表明 AcWL₅在所有三种脂质中形成稳定的、富含肽的凝胶相。AcWL(n)肽的整个家族似乎在所有双层相和厚度下都形成类似的稳定、非破坏膜的β-折叠。含有高达 20 mol%肽的双层，这是测试的最大浓度，形成的凝胶相的熔融温度与纯脂质转变相等或略高。鉴于测试的肽长度和双层厚度范围，这些实验表明，插入膜中的 AcWL(n)家族的β-折叠在膜中表现出显著的结构可塑性。
