Department of Chemistry, Stanford University, Stanford, California 94305, USA.
J Am Chem Soc. 2010 Dec 29;132(51):18367-76. doi: 10.1021/ja108491t. Epub 2010 Dec 8.
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.
肌红蛋白（Mb）双突变体 T67R/S92D 表现出过氧化物酶的酶促活性，与野生型蛋白形成对比。T67R/S92D 的 CO 加合物显示出两个 CO 吸收带，对应于 A(1)和 A(3)亚基。通过二维红外（2D IR）振动回声光谱和分子动力学（MD）模拟研究了 Mb 双突变体的两种不同亚基的平衡蛋白动力学。使用中心线斜率（CLS）方法分析两个亚基的 2D IR 振动回声线形状的时变，以获得频-频相关函数（FFCF）。将双突变体的结果与野生型 Mb 的结果进行比较。将实验确定的 FFCF 与从分子动力学模拟获得的 FFCF 进行比较，从而检验力场确定折叠蛋白结构在快速时间尺度上的结构波动幅度和时间尺度的能力。结果为折叠蛋白结构自由能最小值周围的能量景观的性质提供了深入了解。
