Institute of Chemistry, Martin-Luther-University Halle-Wittenberg, von-Danckelmann-Platz 4, 06120 Halle/Saale, Germany.
Institute of Chemistry, Martin-Luther-University Halle-Wittenberg, von-Danckelmann-Platz 4, 06120 Halle/Saale, Germany.
Biochim Biophys Acta Biomembr. 2017 Mar;1859(3):415-424. doi: 10.1016/j.bbamem.2016.12.019. Epub 2016 Dec 26.
Differential Scanning Calorimetry (DSC) and Fourier transformed Infrared (FT-IR) spectroscopy were used to test the influence of acyl chain length, acyl chain saturation, and chemical structure of anionic phospholipids on the interaction with cationic model peptides (KX)K, with amino acid X=A, Abu, and L. The lipids used were phosphatidylserine (PS), phosphatidylglycerol (PG), phosphatidic acid (PA), and cardiolipin (CL). DSC was used to monitor the phase transition of lipid vesicles before and after peptide binding. The electrostatic attraction is the main driving force for binding. The hydrophobicity of the amino acid X influences the binding strength as well as the secondary structure of the bound peptide. Binding of peptides leads to an upshift of the lipid phase transition. Lipids with smaller headgroups show a larger upshift of the main phase transition temperature. Data from FT-IR spectroscopy show in addition that the stability of the bound β-sheets of (KX)K depends on the hydrophobicity of the uncharged amino acid X and on the size of the lipid headgroup. For lipids with large anionic headgroups, such as PS, the antiparallel β-sheet of (KAbu)K bound to gel phase bilayers is converted to an unordered structure upon heating through the lipid phase transition. Reducing the size of the headgroup, as in PG, increases the stability of the bound peptide β-sheets. For the smallest headgroups, present in PA and CL, stably bound β-sheets are observed even above the lipid phase transition.
差示扫描量热法（DSC）和傅里叶变换红外（FT-IR）光谱用于测试酰基链长、酰基链饱和度和阴离子磷脂的化学结构对与阳离子模型肽（KX）K 相互作用的影响，其中氨基酸 X=A、Abu 和 L。所用的脂质有磷脂酰丝氨酸（PS）、磷脂酰甘油（PG）、磷脂酸（PA）和心磷脂（CL）。DSC 用于监测肽结合前后脂质囊泡的相变。静电吸引是结合的主要驱动力。氨基酸 X 的疏水性影响结合强度以及结合肽的二级结构。肽的结合导致脂质相变上移。具有较小头部基团的脂质显示出较大的主相变温度上移。FT-IR 光谱的数据还表明，（KX）K 结合的β-折叠的稳定性取决于不带电氨基酸 X 的疏水性和脂质头部基团的大小。对于具有大阴离子头部基团的脂质，如 PS，与凝胶相双层结合的（KAbu）K 的反平行β-折叠在通过脂质相变加热时会转化为无序结构。减小头部基团的大小，如 PG，会增加结合肽β-折叠的稳定性。对于最小的头部基团，存在于 PA 和 CL 中，即使在脂质相变之上也观察到稳定结合的β-折叠。
