PICOSECOND OPTICAL STUDIES IN PROTEINS

蛋白质的皮秒光学研究

• 批准号: 3300387
• 负责人: R DWAYNE MILLER
• 金额: $ 13.07万
• 依托单位: UNIVERSITY OF ROCHESTER
• 依托单位国家: 美国
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-12-01 至 1992-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3300387
• 关键词: bioenergetics; biomechanics; chemical models; hemoprotein; heterodyning; holography; image enhancement; molecular dynamics; molecular energy level; myoglobin; photochemistry; protein structure; spectrometry

The specific goal of the proposed research is to determine how vibrational energy propagates in biopolymer systems. The mechanism of energy propagation and dispersion in proteins is central to a microscopic understanding of large amplitude correlated nuclear motion. Structural changes to a specific stimulus are known to be important factors in regulation of activity. Allosteric control of O2 affinity in hemoglobin, muscle contraction and the unwinding of DNA are just a few examples. Biomechanics has long been recognized as an essential component in the regulation of activity. Given the importance of the problem, several theoretical models have been developed to come to grips with the enormous number of nuclei coupled in the motion and the apparent contradiction in time scales for the motions. Theories ranging from nondispersive solitons (vibrational wave packets) to full scale molecular dynamics calculations have been employed. The proposed research constitutes the first direct experimental approach to this problem. Optical excitation in the Soret region of heme proteins provides a selective means to deposit energy into a well defined spatial position in the protein. By use of real-time holography with the novel feature of optical heterodyne detection, the randomization of the optical energy into vibrational modes and the propagation of that energy from the heme center to the protein exterior water layer can be followed with 100 fsec resolution. Optical heterodyne detection acts to amplify the signal and enables the detection of less that 10-80C temperature changes in internal energy. By studying hot band transitions originating spatially from the heme center, tryosine residue in the protein backbone and water exterior, a detailed mapping of the spatial profile and dynamics of the energy propagation can be made. These results can be compared to recent molecular dynamics simulations. Slow structural relaxation processes triggered by CO and O2 photodissociation will also be studied by following changes in the aqueous lattice through density contributions to the real-time holographic image. Emphasis will be place on correlating the first steps in energy transduction during ligand binding or photodissociation to the large amplitude structural responses to the stimulus. These studies will allow for the very first time examination of protein dynamics on all timescales, from the 100 fsec to the msec regime.

拟议研究的具体目标是确定如何振动 能量在生物聚合物系统中传播。 能量机制 在蛋白质中的传播和分散是一个微观的 理解大振幅相关核运动。 结构 已知特定刺激的变化是 规范活动。 血红蛋白中O2亲和力的变构控制， 肌肉收缩和DNA解旋只是几个例子。 生物力学一直被认为是一个重要组成部分， 规范活动。 考虑到问题的严重性， 理论模型已经被开发出来， 在运动中耦合的原子核的数量和 运动的时间尺度。 从非色散孤子 （振动波包）到全尺度分子动力学计算 已经被雇用。 这项研究是第一次直接 实验方法来解决这个问题。 Soret中的光激发 血红素蛋白质的区域提供了一种选择性的手段，以存款能量进入一个 在蛋白质中明确的空间位置。 通过使用实时 全息术具有光外差探测的新特性， 将光能随机化为振动模式， 从血红素中心到蛋白质外部的能量传播 可以以100 Fsec的分辨率跟踪水层。 光外差 检测的作用是放大信号并能够检测到小于 10- 80 ℃温度变化内能。 通过研究热乐队 在空间上起源于血红素中心的转换， 蛋白质骨架和水的外部，空间的详细映射， 可以得到能量传播的轮廓和动力学。 这些结果 可以与最近的分子动力学模拟相比较。 慢结构 由CO和O2光解离引发的弛豫过程也将是 研究通过以下变化的水晶格通过密度 对实时全息图像的贡献。 重点将放在 在配体结合过程中能量传递的第一步 或光解离的大幅度结构响应， 刺激。 这些研究将允许第一次检查 从100飞秒到毫秒范围的所有时间尺度上的蛋白质动力学。