Dynamics of a Myoglobin Mutant Enzyme: 2D IR Vibrational Echo Experiments and Simulations
Dynamics of a Myoglobin Mutant Enzyme: 2D IR Vibrational Echo Experiments and Simulations
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DOI：
10.1021/ja108491t
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发表时间：
2010-12-29
影响因子：
15
通讯作者：
Fayer, M. D.
中科院分区：
文献类型：
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作者：
Bagchi, Sayan;Nebgen, Benjamin T.;Fayer, M. D.
与野生型蛋白相比，肌红蛋白（Mb）双突变体T67R/S92D显示过氧化物酶酶活性。T67R/S92D的CO加合物呈现对应于A(1)和A(3)基态的两条CO吸收带。利用二维红外（2D IR）振动回波光谱和分子动力学（MD）模拟研究了Mb双突变体两种不同底态的平衡蛋白动力学。利用中心线斜率法（CLS）分析了两种基态的二维红外振动回波线形状随时间的变化，得到了频率-频率相关函数（FFCF）。将双突变体的结果与野生型Mb的结果进行了比较。将实验确定的FFCF与分子动力学模拟得到的FFCF进行了比较，从而测试了力场在快速时间尺度上确定蛋白质结构波动幅度和时间尺度的能力。该结果提供了对折叠蛋白质结构的自由能最小值周围的能量景观性质的见解。
Myoglobin (Mb) double mutant T67R/S92D displays peroxidase enzymatic activity in contrast to the wild type protein. The CO adduct of T67R/S92D shows two CO absorption bands corresponding to the A(1) and A(3) substates. The equilibrium protein dynamics for the two distinct substates of the Mb double mutant are investigated by using two-dimensional infrared (2D IR) vibrational echo spectroscopy and molecular dynamics (MD) simulations. The time-dependent changes in the 2D IR vibrational echo line shapes for both of the substates are analyzed using the center line slope (CLS) method to obtain the frequency-frequency correlation function (FFCF). The results for the double mutant are compared to those from the wild type Mb. The experimentally determined FFCF is compared to the FFCF obtained from molecular dynamics simulations, thereby testing the capacity of a force field to determine the amplitudes and time scales of protein structural fluctuations on fast time scales. The results provide insights into the nature of the energy landscape around the free energy minimum of the folded protein structure.