Pechey D T, Graham A B, Wood G C
Biochem J. 1978 Oct 1;175(1):115-24. doi: 10.1042/bj1750115.
Arrhenius plots of the non-latent UDP-glucuronyltransferase (p-nitrophenol acceptor) activity of guinea-pig microsomal membranes prepared with 154 mM-KCl were linear from 5 to 40 degrees C. Arrhenius plots for other microsomal preparations from guinea pig and rat liver that show various degrees of transferase latency, exhibited two linear regions intersecting at a sharp transition point near 20-25 degrees C. This discontinuity was abolished or greatly decreased when transferase latency was removed by treating the membranes with perturbants of phospholipid bilayer strucutre. The fluorescent probe N-phenyl-1-naphthyl-amine detected a thermotropic change in the fluidity of the phospholipid acyl chains of all the microsomal membrane preparations studied, at temperatures close to those of the Arrhenius-plot transitions. It is concluded that the thermotropic change in the structure of the membrane bilayer probably is a 'phase separation' or clustering of phospholipids, which affects a permeability barrier that restricts access of substrate to the transferase molecules.
用154 mM - KCl制备的豚鼠微粒体膜的非潜伏性UDP - 葡萄糖醛酸基转移酶（对硝基苯酚受体）活性的阿累尼乌斯图在5至40摄氏度呈线性。来自豚鼠和大鼠肝脏的其他微粒体制剂的阿累尼乌斯图显示出不同程度的转移酶潜伏性，在接近20 - 25摄氏度处有一个尖锐的转变点，呈现出两个线性区域相交。当用磷脂双层结构扰动剂处理膜以消除转移酶潜伏性时，这种不连续性被消除或大大降低。荧光探针N - 苯基 - 1 - 萘胺在接近阿累尼乌斯图转变温度时，检测到所有研究的微粒体膜制剂的磷脂酰链流动性的热致变化。结论是，膜双层结构的热致变化可能是磷脂的“相分离”或聚集，这影响了限制底物接近转移酶分子的通透性屏障。
