Hoyo Javier, Guaus Ester, Torrent-Burgués Juan, Sanz Fausto
†Department of Chemical Engineering, Universitat Politècnica de Catalunya, 08222 Terrassa (Barcelona), Spain.
‡Institut de Bioenginyeria de Catalunya (IBEC), 08028 Barcelona, Spain.
J Phys Chem B. 2015 May 21;119(20):6170-8. doi: 10.1021/acs.jpcb.5b02196. Epub 2015 May 7.
Photosynthetic organisms use light to convert the inorganic matter in organic one. Photosynthetic process consists on several steps, and one of them involves plastoquinone (PQ) that acts as electron and proton shuttle between photosystem II and cytochrome. We prepared membranes that mimic the characteristics and composition of natural photosynthetic membranes and we characterized them using several techniques in order to obtain both the PQ molecules disposition in the membrane and their electrochemical behavior. The selected lipid was monogalactosyldiacylglycerol (MGDG) that represents the 50% of the lipid content of the thylakoid membrane. Both MGDG and PQ, and the MGDG:PQ mixtures have been studied using surface pressure-area isotherms and the presence of PQ alters the physical state and compactness of the MGDG matrix. Langmuir-Blodgett (LB) films have been obtained by transferring a monolayer that mimics half of the bilayer of a biological membrane. The AFM topographical characterization of the monolayers on mica indicates the presence of differentiated domains, corresponding to different physical states linked to the influence of the PQ content. Moreover, the electrochemical behavior of the monolayers has been studied when transferred on ITO, observing one main electrochemical process that is due to the diving position of PQ molecules in the lipid matrix.
光合生物利用光将无机物转化为有机物。光合作用过程由几个步骤组成，其中一个步骤涉及质体醌（PQ），它在光系统II和细胞色素之间充当电子和质子穿梭体。我们制备了模拟天然光合膜特征和组成的膜，并使用多种技术对其进行表征，以获得PQ分子在膜中的分布及其电化学行为。所选脂质为单半乳糖二酰基甘油（MGDG），它占类囊体膜脂质含量的50%。我们使用表面压力-面积等温线研究了MGDG、PQ以及MGDG与PQ的混合物，PQ的存在改变了MGDG基质的物理状态和紧密程度。通过转移模拟生物膜双层一半的单分子层获得了朗缪尔-布洛杰特（LB）膜。云母上单分子层的原子力显微镜（AFM）形貌表征表明存在不同的区域，这与PQ含量的影响导致的不同物理状态相对应。此外，研究了转移到氧化铟锡（ITO）上的单分子层的电化学行为，观察到一个主要的电化学过程，这是由于PQ分子在脂质基质中的分布位置所致。
