通过31PCODEXNMR测量了两种阳离子肽对POPC与各种阴离子磷脂的二元混合物中磷脂横向扩散的影响。由POPC/POPG(70/30mol/mol)组成的大单层囊泡,或POPC/DOPS(70/30mol/mol),或POPC/TOCL(85/15mol/mol),或POPC/DOPA(50/50mol/mol)暴露于聚赖氨酸(pLYS,N=134单体)或KL-14(KKLLKKAKKLLKL),一种两亲性螺旋肽模型,其用量对应于阳离子赖氨酸残基对阴离子磷脂电荷的80%中和。在没有添加肽的情况下,磷脂横向扩散系数(均在10°C下测量)随温度降低(T-Tm)的增加而增加。POPC/DOPA混合物是这种概括的一个例外,因为这两种成分的横向扩散比研究的任何其他混合物都要慢得多,归因于分子间氢键的作用。pLYS或KL-14的添加减少了POPC/DOPSLUV中的横向扩散,但对POPC/POPGLUV的影响很小,这表明阳离子肽残基容易接近阴离子磷脂基团是重要的。两种阳离子肽在POPC/DOPA情况下产生相反的效果,在它们的存在下,横向扩散显著增加,KL-14是最有效的。后者的观察结果是根据Kooijman等人提出的静电/H键模型来解释的。[生物化学杂志,282:11356-11,364,2007]描述了PA的磷酸单酯头基与赖氨酸的叔胺之间相互作用的机理。
The effects of two cationic peptides on phospholipid lateral diffusion in binary mixtures of POPC with various anionic phospholipids were measured via 31P CODEX NMR. Large unilamellar vesicles composed of POPC/POPG (70/30 mol/mol), or POPC/DOPS (70/30 mol/mol), or POPC/TOCL (85/15 mol/mol), or POPC/DOPA (50/50 mol/mol) were exposed to either polylysine (pLYS, N = 134 monomers) or KL-14 (KKLL KKAKK LLKKL), a model amphipathic helical peptide, in an amount corresponding to 80% neutralization of the anionic phospholipid charge by the cationic lysine residues. In the absence of added peptide, phospholipid lateral diffusion coefficients (all measured at 10 °C) increased with increasing reduced temperature (T-Tm). The POPC/DOPA mixture was an exception to this generalization, in that lateral diffusion for both components was far slower than any other mixture investigated, an effect attributed to intermolecular hydrogen bonding. The addition of pLYS or KL-14 decreased lateral diffusion in the POPC/DOPS LUV, but had minimal effects in the POPC/POPG LUV, indicating that ease of access of the cationic peptide residues to the anionic phospholipid groups was important. Both cationic peptides produced the opposite effect in the POPC/DOPA case, in that lateral diffusion increased significantly in their presence, with KL-14 being most effective. This latter observation was interpreted in terms of the electrostatic / H-bond model proposed by Kooijman et al. [Journal of Biological Chemistry, 282:11356-11,364, 2007] to describe the mechanism of interaction between the phosphomonoester head group of PA and the tertiary amine of lysine.