Shin Y K, Levinthal C, Levinthal F, Hubbell W L
Jules Stein Eye Institute, University of California, Los Angeles 90024.
Science. 1993 Feb 12;259(5097):960-3. doi: 10.1126/science.8382373.
To investigate the mechanism of interaction of the toxin colicin E1 with membranes, three cysteine substitution mutants and the wild type of the channel-forming fragment were spin labeled at the unique thiol. Time-resolved interaction of these labeled proteins with phospholipid vesicles was investigated with stopped-flow electron paramagnetic resonance spectroscopy. The fragment interacts with neutral bilayers at low pH, indicating that the interaction is hydrophobic rather than electrostatic. The interaction occurs in at least two distinct steps: (i) rapid adsorption to the surface; and (ii) slow, rate-limiting insertion of the hydrophobic central helices into the membrane interior.
为了研究毒素大肠杆菌素E1与膜相互作用的机制，对三个半胱氨酸取代突变体和通道形成片段的野生型在其唯一的巯基处进行了自旋标记。利用停流电子顺磁共振光谱研究了这些标记蛋白与磷脂囊泡的时间分辨相互作用。该片段在低pH值下与中性双层膜相互作用，表明这种相互作用是疏水的而非静电的。这种相互作用至少通过两个不同的步骤发生：（i）快速吸附到表面；（ii）疏水中心螺旋缓慢地、限速插入膜内部。
