Protein fluctuations are sensed by stimulated infrared echoes of the vibrations of carbon monoxide and azide probes
Protein fluctuations are sensed by stimulated infrared echoes of the vibrations of carbon monoxide and azide probes
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DOI：
10.1073/pnas.95.26.15315
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发表时间：
1998-12-22
影响因子：
11.1
通讯作者：
Hochstrasser, RM
中科院分区：
文献类型：
--
作者：
Lim, MH;Hamm, P;Hochstrasser, RM
利用飞秒红外脉冲产生的受激光子回波，直接确定了叠氮离子与蛋白质中一氧化碳的振动频率波动的相关函数。叠氮化物与碳酸酐酶II的不对称伸缩振动在几皮秒的时间尺度上表现出明显的振动频率分布演变，这是由于与附近的Thr-199相互作用修饰了配体结构。当叠氮化物结合在血红蛋白中时，需要更复杂的蛋白质结构进化来交换不同的配体构型，在这种情况下，频率分布的弛豫速度要慢得多。血红蛋白中一氧化碳结合频率分布的时间演变发生在大约10-ps的时间尺度上，并且是非指数的。频率波动的相关函数决定了探针局部蛋白质结构的演化，以及探针能够在能量格局中导航的程度，在这些能量格局中，结构配置能够修改探针的局部势能函数。
The correlation functions of the fluctuations of vibrational frequencies of azide ions and carbon monoxide in proteins are determined directly from stimulated photon echoes generated with femtosecond infrared pulses. The asymmetric stretching vibration of azide bound to carbonic anhydrase II exhibits a pronounced evolution of its vibrational frequency distribution on the time scale of a few picoseconds, which is attributed to modifications of the ligand structure through interactions with the nearby Thr-199. When azide is bound in hemoglobin, a more complex evolution of the protein structure is required to interchange the different ligand configurations, as evidenced by the much slower relaxation of the frequency distribution in this case. The time evolution of the distribution of frequencies of carbon monoxide bound in hemoglobin occurs on the approximate to 10-ps time scale and is very nonexponential. The correlation functions of the frequency fluctuations determine the evolution of the protein structure local to the probe and the extent to which the probe can navigate those parts of the energy landscape where the structural configurations are able to modify the local potential energy function of the probe.