PICOSECOND TIME-RESOLVED CRYSTALLOGRAPHY

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。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。列出的机构是 研究中心，而研究中心不一定是研究者所在的机构。 我们的目标是采用皮秒时间分辨劳厄晶体学技术来研究蛋白质的生物物理过程。具体来说，我们将使用强烈的短时间激光脉冲来触发蛋白质晶体的结构变化，并将使用一系列X射线快门用从同步加速器脉冲序列中分离出来的单个X射线脉冲来探测其结构演变。通过在激光光解后的一个明确的瞬间获得衍射数据，我们可以构建蛋白质的快照？的结构与时间分辨率仅限于X射线脉冲的持续时间，这是100 ps的顺序。我们的目标是解决许多生物物理问题，包括高度保守的残基在蛋白质中的功能作用，配体迁移到和从蛋白质的途径？的活性位点，以及介导或控制变构调节的相关结构变化。为了获得尽可能高质量的数据，我们将首先关注结构变化可逆的蛋白质系统。配体结合血红素蛋白，包括肌红蛋白和血红蛋白，是这些生物物理研究的理想模型系统。当CO被用作O2的替代物时，配体可以以高量子效率从血红素中光解，从而触发可以在结构上研究的一系列事件。因为解离的配体在ms时间尺度上双分子地重新结合到血红素，所以结构返回到其起始状态，并且该过程可以重复数千次。因此，这些模型系统是进行这些生物物理研究的理想选择。

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 aim to employ the technique of picosecond time-resolved Laue crystallography to study biophysical processes in proteins. Specifically, we will use intense, short-duration laser pulses to trigger a structural change in a protein crystal, and will probe its structural evolution with single X-ray pulses isolated from the synchrotron pulse train using a sequence of X-ray shutters. By acquiring diffraction data at a well-defined instant in time after laser photolysis, we can construct a snapshot of the protein?s structure with time resolution limited only by the duration of the X-ray pulse, which is of the order of 100 ps. We aim to address numerous biophysical questions including the functional role of highly conserved residues in proteins, pathways for ligand migration to and from the protein?s active site, and the correlated structural changes that mediate or control allosteric regulation. To obtain the highest quality data possible, we will focus initially on protein systems whose structural changes are reversible. Ligand-binding heme proteins, including myoglobin and hemoglobin, are ideal model systems for these biophysical investigations. When CO is used as a surrogate for O2, the ligand can be photodissociated from the heme with high quantum efficiency, thereby triggering a sequence of events that can be studies structurally. Because the dissociated ligands rebind to the heme bimolecularly on the ms time scale, the structure returns to its starting state and the process can be repeated thousands of times. Thus, these model systems are ideal for pursuing these biophysical studies.