LOW FREQUENCY MODES & THEIR ROLE IN EQUILIBRATION

低频模式

• 批准号: 6328062
• 负责人: C M PHILLIPS
• 金额: $ 0.55万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-08-01 至 2001-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6328062
• 关键词: biological products; biomedical resource; proteins

Vibrational transitions are sensitive to temperature (frequency shifts and bandwidth changes) so it is proposed to develop transient IR methods to study heat transport in proteins and other structures in aqueous solutions. In particular, the IR spectrum of water is modified by heating which breaks hydrogen bonds and the proposed methods can measure changes of ca. 0.02 C. In recent experiments the changes in temperature arising from the flow of energy from a heme group was studied. The rise times of the heating signal in deoxyhemoglobin (Hb) and deoxymyoglobin (Mb) solutions were studied in detail to investigate the energy transport mechanisms in heme proteins. The kinetics of this increase of transmission is fitted to a model that consists of a fast and a slow component. The fast component is best fitted by a Gaussian rise function with time constants of 7.5 1 1.5 and 8.5 1 1.5 ps for Mb solution and Hb solutions, respectively. The slow component (ca. 20 ps), with 40% of the total amplitude, was attributed to energy transfer from heme to water through the protein via a classical diffusion process based on agreement between the measured time and that calculated with classical diffusion theory. The fast component, almost identical for both Hb and Mb, could not be described by classical diffusion theory and is suggested to proceed through collecti ve motions of the protein. Experiments on myoglobin (Mb) were also performed to investigate the flow of energy from heme after excitation into different electronic states of the heme. Distinct absorption and bleaching features could be ascribed to vibrationally "hot" heme within the Mb that relaxed with a time constant of 2 to 5 ps.

振动跃迁对温度（频率）敏感 偏移和带宽变化），因此建议开发瞬态 研究蛋白质和其他结构中热传递的红外方法 水溶液。 特别地，水的IR光谱是 通过加热使氢键断裂而改性， 方法可以测量CA的变化。 0.02 C.在最近的实验中， 由血红素的能量流动引起的温度变化 组进行了研究。 加热信号的上升时间 脱氧血红蛋白（Hb）和脱氧肌红蛋白（Mb）溶液进行了研究， 详细研究血红素的能量传递机制 proteins. 这种透射率增加的动力学适合于： 一种由快和慢组成的模型。 快速 分量最好用随时间变化的高斯上升函数拟合 Mb溶液和Hb的7.5 1 1.5和8.5 1 1.5 ps的常数 解决方案，分别。 慢的部分（慢的部分） 20 ps），40%的 总振幅，是由于能量转移从血红素， 水通过蛋白质通过经典的扩散过程， 测量时间与经典计算时间一致 扩散理论 快成分，几乎相同的两个血红蛋白 和Mb，不能用经典扩散理论描述， 建议通过蛋白质的集体运动进行。 对肌红蛋白（Mb）的实验也进行了研究， 能量从血红素在激发后流入不同的电子 血红素的状态。 独特的吸收和漂白特性， 被归因于振动“热”血红素内的Mb，放松 时间常数为2到5ps。