Time-resolved detection of conformational changes in oat phytochrome A: Time-dependent diffusion
Time-resolved detection of conformational changes in oat phytochrome A: Time-dependent diffusion
复制标题
DOI：
10.1529/biophysj.106.092882
复制
发表时间：
2006-11-01
影响因子：
3.4
通讯作者：
Terazima, Masahide
中科院分区：
文献类型：
--
作者：
Eitoku, Takeshi;Zarate, Xristo;Terazima, Masahide
通过脉冲激光诱导瞬态光栅技术在时域研究了红色吸收形式 (Pr) 光激发后溶液中燕麦光敏色素 A (phy) 的构象变化。结果发现，与Pr (5.8 x 10(-11) m(2) s(-1))相比，大phy (1.3 x 10(-11) m(2) s(-1))的远红光吸收形式(Pfr)的扩散系数(D)显着降低。这种大幅减少表明Pfr的构象与Pr相比发生了显着变化，从而与水分子的分子间相互作用增加。这种变化在光激发后 1 毫秒内完成。另一方面，完整phy的Pr的D (4.1 x 10(-11) m(2) s(-1))首先在光激发时在1 ms内减小到0.89 x 10(-11) m 2 s(-1)，然后以100 ms的时间常数逐渐增加到Pfr的值，1.7 x 10(-11) m(2) s(-1)。这个较慢的阶段表明，在大 phy 区域发生全局变化后，N 端区域的构象会发生 100 ms 的变化，从而减少与水的分子间相互作用。 D 的增加可以根据 Pr 形式的无规卷曲结构形成 Pfr 形式的 α 螺旋来解释。
Conformational changes in oat phytochrome A (phy) in solution after photoexcitation of the red-absorbing form (Pr) were studied in time-domain by the pulsed laser-induced transient grating technique. It was found that the diffusion coefficient (D) of far-red-absorbing form (Pfr) of large phy (1.3 x 10(-11) m(2) s(-1)) is markedly reduced compared with that of Pr (5.8 x 10(-11) m(2) s(-1)). This large reduction indicates that the conformation of Pfr is significantly changed from that of Pr, so that the intermolecular interaction with water molecules increases. This change completes within 1 ms after the photoexcitation. On the other hand, D of Pr of intact phy (4.1 x 10(-11) m(2) s(-1)) first decreases upon photoexcitation to 0.89 x 10(-11) m 2 s(-1) within 1 ms and then gradually increases with a time constant of 100 ms to the value of Pfr, 1.7 x 10(-11) m(2) s(-1). This slower phase suggests that the conformation of the N-terminal region changes with 100 ms to decrease the intermolecular interaction with water after a global change in the large phy region. The increase of D was interpreted in terms of alpha-helix formation in the Pfr form from the random coil structure in the Pr form.