The excimer fluorescence of pyrene-labeled tropomyosin. A probe of conformational dynamics.
The excimer fluorescence of pyrene-labeled tropomyosin. A probe of conformational dynamics.
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DOI：
10.1016/s0021-9258(19)70290-7
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发表时间：
1980-12
期刊：
影响因子：
--
通讯作者：
P. Graceffa;S. Lehrer
中科院分区：
文献类型：
--
作者：
P. Graceffa;S. Lehrer
用N-（1-芘）-马来酰亚胺特异性标记兔骨骼肌和心肌原肌球蛋白的半胱氨酸侧链。通过荧光技术观察到由于每条链的Cys 190上的相邻芘之间的相互作用而形成高度的分子内激基缔合物。该改性在低盐下产生低的比粘度值，表明盐依赖性聚合性的抑制。尽管聚合性的损失，准分子荧光的芘原肌球蛋白增加了类似的盐依赖性的粘度的降低未标记的控制。对标记的原肌球蛋白的瞬态和稳态荧光测量表明存在两种状态的标记的原肌球蛋白，准分子形成状态（状态B）和非准分子形成状态（状态A），彼此平衡。受激准分子随温度和盐浓度的增加而增加，这可以用平衡向状态B的移动来解释。空间上的考虑表明，为了使芘形成受激准分子，需要在状态B中的局部链分离。
Rabbit skeletal and cardiac tropomyosin were specifically labeled at their cysteine side chains with N-(1-pyrene)-maleimide. A high degree of intramolecular excimer formation due to interaction between adjacent pyrenes on Cys 190 of each chain was observed by fluorescence techniques. This modification produced low values of specific viscosity at low salt, indicating an inhibition of the salt-dependent polymerizability. Despite the loss of polymerizability, the excimer fluorescence of pyrene-tropomyosin increased with a similar salt dependence as the decrease in viscosity of an unlabeled control. Transient and steady state fluorescence measurements on the labeled tropomyosin indicated the presence of two states of labeled tropomyosin, an excimer-forming state (State B) and a nonexcimer-forming state (State A), in equilibrium with each other. The increase in excimer with increasing temperature and salt concentration can be explained by a shift in equilibrium toward State B. Steric considerations suggest that, in order for the pyrenes to form an excimer, localized chain separation in State B is required.