COHERENT INFRARED METHODS FOR STRUCTURAL FLUCTUATIONS

用于结构波动的相干红外方法

• 批准号: 7373124
• 负责人: ROBIN Main HOCHSTRASSER
• 金额: $ 8.13万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-01 至 2007-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7373124
• 关键词: COHERENT; INFRARED; METHODS; STRUCTURAL; FLUCTUATIONS

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We continue to develop and refine the methods of coherent infrared photon echo spectroscopy to examine structural fluctuations in peptides and proteins through their vibrational correlation functions. Heterodyned transient gratings and three pulse photon echo methods for determining vibrational frequency correlation functions are now being evaluated to optimize the signal to noise ratio and extend the time scales over which the structural relaxation can be examined. We are also developing methods to determine the correlations between the structure fluctuations at different spatial locations of a wide variety of secondary structures. We have developed 2D-IR and 3D-IR methods in the region of the N-H and O-H (and isotopic variants) stretch modes. Combined amide-I and amide-A four-wave experiments have been accomplished in which couplings between remote N-H and amide carbonyls have been determined. Infrared methods with appropriate band width and time resolution have been developed to measure (i) The overall protein rotation, based on intrinsic probes; (ii) the motion of the chromophore as a whole relative to the protein; (iii) the orientational motion of the particular IR active bond; (iv) both the order parameters and time constants for these motions; (v) correlations between infrared absorption and chromophore absorption; (vi) correlations between different IR transitions of the same species (e.g. amino acid); (vii) probing the amide-I substructure by dynamic hole-burning and (viii) infrared photon echo measurements. The Resource has proved the principle of a number of important experiments aimed at using molecular vibrational transitions to study molecular reorientation, in particular internal rotations. The basic idea is to excite a bond vibration with a polarized IR pulse and probe it with another polarized IR pulse at a later time. The ensemble average of the projection of the initial dipole onto itself at later time is the orientational correlation function of the bond. To further utilize these techniques, we are combining the 2D-IR technology with laser-based T-jump methods. We are exploring methods of generating the pulses that can be directly absorbed into the overtone bands of the solvent water or D2O. The temperature jump method will be applied to induce conformational changes associated with unfolding/folding in proteins and peptides, probed with our 2D IR technique. A study of the T-jump induced folding dynamics of the villian head piece using this combined 2D IR/T-jump approach is under way in our laboratories.

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。我们继续发展和完善相干红外光子回波光谱的方法，通过它们的振动相关函数来检查肽和蛋白质的结构波动。外差瞬态光栅和三个脉冲光子回波方法确定振动频率的相关函数，现在正在评估，以优化信号噪声比，并延长时间尺度的结构松弛可以检查。我们也正在开发方法来确定各种各样的二级结构的不同空间位置的结构波动之间的相关性。我们已经开发了二维红外和三维红外方法在该地区的N-H和O-H（和同位素变体）的拉伸模式。结合酰胺-I和酰胺-A的四波实验已经完成，其中远程N-H和酰胺羰基之间的耦合已被确定。已经开发了具有适当带宽和时间分辨率的红外方法来测量（i）基于内在探针的总蛋白质旋转;（ii）发色团作为整体相对于蛋白质的运动;（iii）特定IR活性键的取向运动;（iv）这些运动的序参数和时间常数;（v）红外吸收和发色团吸收之间的相关性;（v）红外吸收和发色团吸收之间的相关性。（vi）相同物种（例如氨基酸）的不同IR跃迁之间的相关性;（vii）通过动态烧孔探测酰胺-I亚结构;和（viii）红外光子回波测量。该资源证明了一些旨在利用分子振动跃迁研究分子重新定向，特别是内部旋转的重要实验的原理。其基本思想是用一个偏振的红外脉冲激发一个键振动，然后用另一个偏振的红外脉冲探测它。初始偶极在以后的时间内在自身上的投影的系综平均值是键的取向相关函数。 为了进一步利用这些技术，我们将2D-IR技术与基于激光的T跳跃方法相结合。我们正在探索产生可以直接吸收到溶剂水或D2 O泛音带中的脉冲的方法。温度跳跃方法将被应用于诱导构象变化与展开/折叠的蛋白质和肽，探测与我们的二维红外技术。我们的实验室正在使用这种组合的2D IR/T-jump方法研究Villian头片的T-jump诱导的折叠动力学。