Becucci Lucia, León Reyes Romero, Moncelli Maria Rosa, Rovero Paolo, Guidelli Rolando
Department of Chemistry, Florence University, Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy.
Langmuir. 2006 Jul 18;22(15):6644-50. doi: 10.1021/la060681x.
The channel-forming peptide melittin was incorporated into a biomimetic membrane consisting of a mercury electrode coated with a thiolipid monolayer, with a lipid monolayer self-assembled on top of it. The thiolipid consisted of a hydrophilic tetraethyleneoxy chain terminated at one end with a disulfide group, for anchoring to the mercury surface, and covalently linked at the other end to two diphytanyl chains, which formed a lipid bilayer with the overhanging lipid monolayer. The conductance of the lipid bilayer in contact with aqueous 0.1 M KCl was measured by electrochemical impedance spectroscopy over a frequency range from 1 x 10(-2) to 1 x 10(5) Hz and a potential range of 0.7 V for different compositions of the outer lipid monolayer. The conductance increases abruptly above the background level at sufficiently negative applied potentials, attaining a maximum value that increases with the composition of the outer monolayer in the order PC/chol (60:40) < PC < PC/SM/chol (59:15:26) < PS, with PC = phosphatidylcholine, chol = cholesterol, SM = sphingomyelin, and PS = phosphatidylserine. The higher the maximum conductance, the less negative the applied potential at which it is attained. This behavior is also discussed using a model of the electrified interphase.
形成通道的肽蜂毒肽被整合到一种仿生膜中，该仿生膜由涂有硫脂单层的汞电极组成，在其顶部有一个自组装的脂质单层。硫脂由一个亲水的四乙烯氧基链组成，一端以二硫基团终止，用于锚定在汞表面，另一端与两条二植烷基链共价连接，这两条链与悬垂的脂质单层形成脂质双层。通过电化学阻抗谱在1×10(-2)至1×10(5)Hz的频率范围和0.7V的电位范围内，对与0.1M KCl水溶液接触的脂质双层的电导进行了测量，测量对象为不同组成的外部脂质单层。在足够负的外加电位下，电导会突然高于背景水平，达到一个最大值，该最大值随外部单层的组成按以下顺序增加：PC/胆固醇(60:40)<PC<PC/鞘磷脂/胆固醇(59:15:26)<PS，其中PC=磷脂酰胆碱，chol=胆固醇，SM=鞘磷脂，PS=磷脂酰丝氨酸。最大电导越高，达到该最大值时的外加电位越不那么负。还使用带电界面模型对这种行为进行了讨论。
