Busi Elena, Vitiello Giuseppe, Niccoli Marcella, Basosi Riccardo, Montesarchio Daniela, D'Errico Gerardino
Dipartimento Biotecnologie, Chimica e Farmacia, Università di Siena, Siena, Italy.
Biochim Biophys Acta. 2013 Sep;1828(9):2074-82. doi: 10.1016/j.bbamem.2013.05.017. Epub 2013 May 26.
The mechanism underlying the ionophoric activity of CyPLOS (cyclic phosphate-linked oligosaccharide, 2), a carbohydrate-based synthetic ion transporter decorated with four tetraethylene glycol (TEG) chains, has been investigated by an integrated electron spin resonance (ESR) approach. The mode of interaction of the ionophore with lipid bilayers has been studied by quantitatively analyzing the perturbations in the ESR spectrum of an ad hoc synthesized spin-labeled CyPLOS analog (6), and, in parallel, in the spectra of spin-labeled lipids mixed with 2. The results point to a positioning of the cyclic saccharide backbone close to the lipid headgroups, largely exposed to the aqueous medium. The TEG chains, carrying a terminal benzyl group, are deeply inserted among the lipid acyl chains, showing good mobility and flexibility. As a consequence, the order of the acyl chain packing is significantly reduced, and water penetration in the bilayer is enhanced. The resulting asymmetric perturbation of the bilayer leads to its local destabilization, thus facilitating, through a non-specific mechanism, the ion transport through the membrane.
通过综合电子自旋共振（ESR）方法，对一种带有四条四甘醇（TEG）链的基于碳水化合物的合成离子转运体CyPLOS（环磷酸连接的寡糖，2）的离子载体活性潜在机制进行了研究。通过定量分析一种专门合成的自旋标记CyPLOS类似物（6）的ESR谱中的扰动，并同时分析与2混合的自旋标记脂质的谱，研究了离子载体与脂质双层的相互作用模式。结果表明，环状糖骨架靠近脂质头部基团定位，在很大程度上暴露于水介质中。带有末端苄基的TEG链深深地插入脂质酰基链之间，显示出良好的流动性和柔韧性。因此，酰基链堆积的有序性显著降低，双层中的水渗透增强。双层由此产生的不对称扰动导致其局部不稳定，从而通过非特异性机制促进离子通过膜的运输。
