Department of Physiology and Pharmacology, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel.
Biophys J. 1999 Nov;77(5):2764-76. doi: 10.1016/S0006-3495(99)77109-2.
Weak anharmonic coupling of two soft molecular vibrations is shown to cause pronounced temperature dependence of the corresponding resonance Raman bands. The developed theory is used to interpret the temperature dependence of the iron-histidine band of deoxyheme proteins and model compounds. It is shown that anharmonic coupling of the iron-histidine and heme doming vibrations must cause pronounced broadening of the band, its asymmetry, and shift of its maximum to the red upon heating. It also can lead to a structured shape of this band at room temperature. Proper consideration of the anharmonic coupling allows simulation of the temperature dependence of the iron-histidine band shape of horse heart myoglobin in the temperature interval of 10-300 K, using the minimum number of necessary parameters. Analysis of this temperature dependence clearly shows that the iron-histidine band of deoxyheme proteins is sensitive to the glass-liquid phase transition in the protein hydration shell, which takes place at 160-190 K.
两个软分子振动的弱非谐耦合被证明会导致相应的共振拉曼带的显著温度依赖性。所发展的理论被用于解释脱氧血红素蛋白和模型化合物中铁-组氨酸带的温度依赖性。结果表明，铁-组氨酸和血红素凸起振动的非谐耦合必然会导致带的显著展宽、不对称性以及在加热时最大位移向红移。它还可以导致该带在室温下具有结构化的形状。适当考虑非谐耦合，可以使用最少的必要参数模拟马心肌红蛋白中铁-组氨酸带形状在 10-300 K 温度范围内的温度依赖性。对这种温度依赖性的分析清楚地表明，脱氧血红素蛋白的铁-组氨酸带对蛋白质水合壳中的玻璃-液相转变敏感，该转变发生在 160-190 K。
