5-D CRYSTALLOGRAPHY SPACE TIME AND TEMPERATURE

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 五维结晶学 时间分辨结晶学最适合于在原子长度尺度上实时跟踪反应。它结合了结晶学和化学动力学。已经做出了大量努力来收集在时间上连续的几个数量级的数据集。由此可以利用奇异值分解等先进的数学方法来推断中间体的结构和化学动力学机理。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，因此它们是退化的。为了消除这种简并性，必须改变一个附加参数，以确定描述唯一机制的唯一速率系数集。由于速率系数通常遵循阿累尼乌斯定律，因此需要改变温度。 因此，4维的时间分辨结晶学--3个空间维度加上时间--将变成5维。 我们将首次使用以前通过光谱学和时间分辨结晶学手段很好地表征的光活性黄色蛋白的晶体来进行这类实验。使用奇异值分解，结构转变的松弛时间将在从-5℃到35℃的几个温度下使用每个温度下的结晶Laue数据的时间序列来确定。最终，这将给出一组独特的、明显可区分的中间体，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. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. 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.