Pattison S E, Telles S, Friar S, Stowell C, Beckley R
Department of Chemistry, Ball State University, Muncie, Indiana 47306, USA.
Arch Biochem Biophys. 1998 Mar 1;351(1):41-6. doi: 10.1006/abbi.1997.0558.
Zinc diffusion across liposome bilayers was measured for a set of phosphatidylcholines. These lipids were sonicated to form small unilamellar vesicles in the presence of the metallochromic indicator antipyrylazo III. This chelator sequentially forms two complexes with zinc ion. The rate constant for the first complex formation is shown to increase linearly with zinc concentration. The slope of this line, a [Zn2+]-independent, second-order rate constant, varies with changes in phosphatidylcholine properties. The rate constant is little affected by changes in fluidity as estimated from the reduced temperature [Tr = (Texperimental-Tc)/Tc]. In contrast, the rate constant is directly dependent on lipid oxidation as measured by either a thiobarbituric acid test or a spectrophotometric determination of conjugate dienes. We estimate that zinc diffusion stimulated by lipid oxidation can approach rates observed in hepatocyte zinc transport.
对一组磷脂酰胆碱测定了锌在脂质体双层中的扩散情况。在金属显色指示剂安替比拉宗III存在下，将这些脂质超声处理以形成小单层囊泡。这种螯合剂与锌离子依次形成两种络合物。已表明第一种络合物形成的速率常数随锌浓度呈线性增加。这条线的斜率，即一个与[Zn2+]无关的二级速率常数，会随磷脂酰胆碱性质的变化而改变。从降低的温度[Tr = (实验温度 - Tc)/Tc]估算，流动性的变化对速率常数影响很小。相比之下，通过硫代巴比妥酸试验或共轭二烯的分光光度法测定，速率常数直接取决于脂质氧化。我们估计，脂质氧化刺激的锌扩散速率可接近在肝细胞锌转运中观察到的速率。
