Ohyashiki T, Karino T, Suzuki S, Matsui K
Department of Clinical Chemistry, Faculty of Pharmaceutical Sciences, Hokuriku University, Ishikawa.
J Biochem. 1996 Nov;120(5):895-900. doi: 10.1093/oxfordjournals.jbchem.a021503.
The effects of Al3+ on Fe(2+)-induced lipid peroxidation in phospholipid liposomes consisting of phosphatidylcholine (PC) and phosphatidylserine (PS) were examined under acidic conditions. The stimulatory effect of Al3+ on Fe(2+)-induced lipid peroxidation in the liposomes showed a biphasic response against pH variation, and the maximum stimulation was observed around pH 6.0. In addition, it was found that the stimulatory effect of Al3+ on the lipid peroxidation was dependent on the proportion of PS in the liposomes. On the other hand, the lipid peroxidation in PC liposomes was not stimulated by the addition of Al3+. From these findings, it is suggested that the Al3+ effect on Fe(2+)-induced lipid peroxidation under acidic conditions is largely dependent on the phospholipid composition. Trivalent cations such as Tb3+ and Ga3+ also stimulated Fe(2+)-induced lipid peroxidation in PC/PS liposomes under acidic conditions, but divalent cations (Zn2+ and Mn2+) showed no stimulatory effect. The extents of Fe2+ disappearance and Fe3+ formation during the reaction were enhanced by the addition of Al3+ or Ga2+, but Tb3+ had no effect on Fe2+ disappearance. The results with 1,6-diphenyl-1,3,5-hexatriene (DPH) showed that the fluorescence anisotropy of DPH-labeled PC/PS liposomes under acidic conditions was increased by the addition of Al3+. Furthermore, there is a relation between the extents of the fluorescence anisotropy of the complex and TBARS production. In contrast, the fluorescence anisotropy of DPH molecules embedded in PC liposomes was not changed by the addition of Al3+. Based on these results, a possible mechanism of the stimulatory effect of Al3+ on Fe(2+)-induced lipid peroxidation under acidic conditions is discussed.
在酸性条件下，研究了Al3+对由磷脂酰胆碱（PC）和磷脂酰丝氨酸（PS）组成的磷脂脂质体中Fe(2+)诱导的脂质过氧化的影响。Al3+对脂质体中Fe(2+)诱导的脂质过氧化的刺激作用对pH变化呈现双相响应，在pH 6.0左右观察到最大刺激作用。此外，发现Al3+对脂质过氧化的刺激作用取决于脂质体中PS的比例。另一方面，添加Al3+不会刺激PC脂质体中的脂质过氧化。基于这些发现，表明酸性条件下Al3+对Fe(2+)诱导的脂质过氧化的影响在很大程度上取决于磷脂组成。三价阳离子如Tb3+和Ga3+在酸性条件下也会刺激PC/PS脂质体中Fe(2+)诱导的脂质过氧化，但二价阳离子（Zn2+和Mn2+）没有刺激作用。反应过程中Fe2+消失和Fe3+形成的程度通过添加Al3+或Ga2+而增强，但Tb3+对Fe2+消失没有影响。用1,6-二苯基-1,3,5-己三烯（DPH）得到的结果表明，酸性条件下添加Al3+会增加DPH标记的PC/PS脂质体的荧光 anisotropy。此外，复合物的荧光anisotropy程度与硫代巴比妥酸反应物（TBARS）生成之间存在关系。相反，添加Al3+不会改变嵌入PC脂质体中的DPH分子的荧光anisotropy。基于这些结果，讨论了酸性条件下Al3+对Fe(2+)诱导的脂质过氧化的刺激作用的可能机制。
