Fiorini Rosamaria, Ragni Letizia, Ambrosi Simona, Littarru Gian Paolo, Gratton Enrico, Hazlett Theodore
Biochemistry Institute, Marche Polytechnic University, Ancona, Italy.
Photochem Photobiol. 2008 Jan-Feb;84(1):209-14. doi: 10.1111/j.1751-1097.2007.00221.x.
Ubiquinone-10 plays a central role in energy production and its reduced form, ubiquinol-10 is also capable of acting as a potent radical scavenging antioxidant against membrane lipid peroxidation. Efficiency of this protection depends mostly on its localization in lipid bilayer. The intrinsic fluorescence of ubiquinol-10 and of the exogenous probe, Laurdan, has been used to determine the location of ubiquinol-10 in unilamellar liposomes of egg phosphatidylcholine (EggPC) and dimyristoyl phosphatidylcholine. Laurdan fluorescence moiety is positioned at the hydrophilic-hydrophobic interface of the phospholipid bilayer and its parameters reflect the membrane polarity and microheterogeneity, which we have used to explore the coexistence of microdomains with distinct physical properties. In liquid-crystalline bilayers ubiquinol has a short fluorescence lifetime (0.4 ns) and a high steady-state anisotropy. In a concentration-dependent manner, ubiquinol-10 influences the Laurdan excitation, emission and generalized polarization measurements. In EggPC liposomes ubiquinol-10 induces a decrease in membrane water mobility near the probe, while in dimyristoyl liposomes a decrease in the membrane water content was found. Moreover the presence of ubiquinol results in the formation of coexisting phospholipid domains of gel and liquid-crystalline phases. The results indicate that ubiquinol-10 molecules are mainly located at the polar-lipid interface, inducing changes in the physico-chemical properties of the bilayer microenvironment.
辅酶Q10在能量产生中起着核心作用，其还原形式辅酶Q10也能够作为一种强大的自由基清除抗氧化剂，抵抗膜脂质过氧化。这种保护作用的效率主要取决于其在脂质双层中的定位。辅酶Q10和外源性探针劳丹的固有荧光已被用于确定辅酶Q10在卵磷脂（EggPC）和二肉豆蔻酰磷脂酰胆碱单层脂质体中的位置。劳丹荧光部分位于磷脂双层的亲水-疏水界面，其参数反映了膜极性和微不均一性，我们已用这些参数来探索具有不同物理性质的微区的共存情况。在液晶双层中，辅酶Q10具有较短的荧光寿命（0.4纳秒）和较高的稳态各向异性。辅酶Q10以浓度依赖的方式影响劳丹的激发、发射和广义极化测量。在EggPC脂质体中，辅酶Q10导致探针附近膜水流动性降低，而在二肉豆蔻酰脂质体中，发现膜水含量降低。此外，辅酶Q10的存在导致凝胶相和液晶相共存的磷脂域形成。结果表明，辅酶Q10分子主要位于极性脂质界面，诱导双层微环境物理化学性质的变化。
