Quinn P J, Esfahani M A
Biochem J. 1980 Mar 1;185(3):715-22. doi: 10.1042/bj1850715.
Surface-active properties of ubiquinones and ubiquinols have been investigated by monomolecular-film techniques. Stable monolayers are formed at an air/water interface by the fully oxidized and reduced forms of the coenzyme; collapse pressures and hence stability of the films tend to increase with decreasing length of the isoprenoid side chain and films of the reduced coenzymes are more stable than those of their oxidized counterparts. Ubiquinone with a side chain of two isoprenoid units does not form stable monolayers at the air/water interface. Mixed monolayers of ubiquinol-10 or ubiquinone-10 with 1,2-dimyristoyl phosphatidylcholine, soya phosphatidylcholine and diphosphatidylglycerol do not exhibit ideal mixing characteristics. At surface pressures less than the collapse pressure of pure ubiquinone-10 monolayers (approx. 12mN.m(-1)) the isoprenoid chain is located substantially within the region occupied by the fatty acyl residues of the phospholipids. With increasing surface pressure the ubiquinones and their fully reduced equivalents are progressively squeezed out from between the phospholipid molecules until, at a pressure of about 35mN.m(-1), the film has surface properties consistent with that of the pure phospholipid monolayer. This suggests that the ubiquinone(ol) forms a separate phase overlying the phospholipid monolayer. The implications of this energetically poised situation, where the quinone(ol) is just able to penetrate the phospholipid film, are considered in terms of the function of ubiquinone(ol) as electron and proton carriers of energy-transducing membranes.
已经通过单分子膜技术研究了泛醌和泛醇的表面活性特性。辅酶的完全氧化形式和还原形式在空气/水界面形成稳定的单分子层；随着异戊二烯侧链长度的减少，膜的崩溃压力以及因此膜的稳定性趋于增加，并且还原型辅酶的膜比其氧化对应物的膜更稳定。具有两个异戊二烯单元侧链的泛醌在空气/水界面不形成稳定的单分子层。泛醇-10或泛醌-10与1,2-二肉豆蔻酰磷脂酰胆碱、大豆磷脂酰胆碱和二磷脂酰甘油的混合单分子层不表现出理想的混合特性。在表面压力小于纯泛醌-10单分子层的崩溃压力（约12mN·m⁻¹）时，异戊二烯链基本上位于磷脂脂肪酰基残基占据的区域内。随着表面压力的增加，泛醌及其完全还原的等价物逐渐从磷脂分子之间被挤出，直到在约35mN·m⁻¹的压力下，膜具有与纯磷脂单分子层一致 的表面性质。这表明泛醌（醇）在磷脂单分子层上方形成一个单独的相。根据泛醌（醇）作为能量转换膜的电子和质子载体的功能，考虑了这种能量平衡情况的含义，即醌（醇）刚好能够穿透磷脂膜。
