5-D CRYSTALLOGRAPHY, SPACE, TIME AND TEMPERATURE

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。子项目及 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 5-三维晶体学 时间分辨晶体学最适合于在真实的时间和原子长度尺度上跟踪反应。它结合了晶体学和化学动力学。已作出了大量努力，收集数据集连续几个数量级的时间。由此，可以使用诸如奇异值分解的高级数学方法来推断中间体的结构以及化学动力学机制。然而，事实证明，这些机制的几个候选者同样很好地解释了数据，因此它们是简并的。为了去除这种简并性，必须改变附加参数以确定描述独特机制的一组独特速率系数。由于速率系数通常遵循阿耳忒弥斯定律，因此需要改变温度。 因此，时间分辨晶体学，这是4维- 3空间维度加上时间-将成为5维。 我们将首次使用光活性黄色蛋白晶体进行此类实验，该晶体以前通过光谱学和时间分辨晶体学进行了很好的表征。使用奇异值分解，结构转变的弛豫时间将使用每个温度下的晶体学劳厄数据的时间序列在从-5 ° C到35 ° C的几个温度下确定。最终，这将给出一组独特的可清楚区分的中间体以及PYP光循环的相应机制。

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. 5-dimensional crystallography Time-resolved crystallography is most suited to follow reactions in real time and on the atomic length scale. It combines crystallography with chemical kinetics. Substantial effort has been made to collect data sets contiguous over several orders of magnitudes in time. From this the structures of the intermediates as well as the chemical kinetic mechanism may be deduced using advanced mathematical methods such as the singular value decomposition. However, it turns out, that several candidates of these mechanisms explain the data equally well, hence they are degenerate. To remove this degeneracy, an additional parameter has to be varied to determine a unique set of rate coefficients describing a unique mechanism. Since rate coefficients usually follow Arrhenius's law, the temperature needs to be varied. Hence time-resolved crystallography, which is 4-dimensional - 3 space dimensions plus the time- would become 5-dimensional. We will perform these kind of experiments for the first time using crystals of photo-active yellow protein, which was previously well characterized by means of spectroscopy and time-resolved crystallography. Using singular value decomposition, relaxation times for the structural transitions will be determined at several temperatures starting at -5 deg C up to 35 deg C using the time-series of crystallographic Laue data at each temperature. Ultimately, this will give a unique set of clearly distinguishable intermediates plus the corresponding mechanism of the PYP photocycle.