Primary protein response after ligand photodissociation in carbonmonoxy myoglobin
Primary protein response after ligand photodissociation in carbonmonoxy myoglobin
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DOI：
10.1073/pnas.0611560104
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发表时间：
2007-06-05
影响因子：
11.1
通讯作者：
Mizutani, Yasuhisa
中科院分区：
文献类型：
--
作者：
Sato, Akira;Gao, Ying;Mizutani, Yasuhisa
对WT和突变肌红蛋白进行时间分辨紫外共振拉曼（UVRR）光谱研究，以揭示配体解离后蛋白质运动的动力学。一氧化碳（CO）从血红素解离后，酪氨酸的UVRR带强度下降，时间常数为2 ps。强度降低之后是强度恢复，时间常数为8 ps。另一方面，位于A螺旋中的色氨酸残基的UVRR带显示在仪器响应时间内完成的强度降低。强度降低之后是强度恢复，时间常数约为50 ps，持续时间长达1 ns。肌红蛋白突变体的时间分辨UVRR研究表明，周围的Trp-14的疏水性环境下降，而周围的Trp-7几乎没有改变的主要蛋白质的反应。目前的数据表明，E螺旋向血红素的位移发生在仪器响应时间内，FG角的移动以2 ps的时间常数发生。E螺旋的瞬时运动的发现强烈地暗示了蛋白质结构变化通过E螺旋运动从血红素传播到A螺旋的机制。
Time-resolved UV resonance Raman (UVRR) spectroscopic studies of WT and mutant myoglobin were performed to reveal the dynamics of protein motion after ligand dissociation. After dissociation of carbon monoxide (CO) from the heme, UVRR bands of Tyr showed a decrease in intensity with a time constant of 2 ps. The intensity decrease was followed by intensity recovery with a time constant of 8 ps. On the other hand, UVRR bands of Trp residues located in the A helix showed an intensity decrease that was completed within the instrument response time. The intensity decrease was followed by an intensity recovery with a time constant of approximate to 50 ps and lasted up to 1 ns. The time-resolved UVRR study of the myoglobin mutants demonstrated that the hydrophobicity of environments around Trp-14 decreased, whereas that around Trp-7 barely changed in the primary protein response. The present data indicate that displacement of the E helix toward the heme occurs within the instrument response time and that movement of the FG corner takes place with a time constant of 2 ps. The finding that the instantaneous motion of the E helix strongly suggests a mechanism in which protein structural changes are propagated from the heme to the A helix through the E helix motion.