Non-contact luminescence lifetime cryothermometry for macromolecular crystallography.
Non-contact luminescence lifetime cryothermometry for macromolecular crystallography.
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DOI：
10.1107/s1600577517003484
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发表时间：
2017-05-01
影响因子：
2.5
通讯作者：
Kraus H
中科院分区：
文献类型：
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作者：
Mykhaylyk VB;Wagner A;Kraus H
介绍了一种利用微型双锗酸盐闪烁传感器远程监测蛋白质晶体温度至10 K的系统的概念和实际实现。在利用强电离辐射的实验中，为了将对生物样品的辐射损害降到最低，温度是一个非常重要的参数。为钻石光源的新i23光束线开发了一种远程、非接触、现场监测蛋白质晶体温度的新技术，钻石光源是一家专门用于长波长X射线大分子结晶学(MX)的设施。该温度是从非常接近被测样品的微小闪烁传感器(<；0.05 mm~3)发出的发光随温度变化的衰减时间常数得出的。本文介绍了低温发光寿命测温的基本原理，讨论了检测方法的特点和温度传感器的选择，并演示了温度监测系统如何集成到用于蛋白质晶体可视化的终端观察系统中。利用Bi4Ge3O12晶体闪烁体对该测温系统进行了表征，该系统在较宽的温度范围内(8-270 K)对衰变时间常数具有良好的响应性。对闪烁传感器进行了标定，在光束线主要工作温度范围(30-150 K)内的温度测量不确定度为±1.6 K。用发光传感器测量的样品架温度与预期值吻合良好。这项技术被应用于表征已经在i23光束线上进行的MX实验中使用的不同样品支架的热性能。结果表明，支架的厚度对样品支架上的温度分布影响最大。总而言之，这些测试和发现表明，测温系统在突出真空MX实验成为结构生物学可靠和不可或缺的工具方面仍需解决的挑战方面是有用的。
The concept and practical implementation of a system for remote monitoring of the temperature of protein crystals down to 10 K using a microscopic bismuth germanate scintillation sensor are presented. Temperature is a very important parameter when aiming to minimize radiation damage to biological samples during experiments that utilize intense ionizing radiation. A novel technique for remote, non-contact, in situ monitoring of the protein crystal temperature has been developed for the new I23 beamline at the Diamond Light Source, a facility dedicated to macromolecular crystallography (MX) with long-wavelength X-rays. The temperature is derived from the temperature-dependent decay time constant of luminescence from a minuscule scintillation sensor (<0.05 mm3) located in very close proximity to the sample under test. In this work the underlying principle of cryogenic luminescence lifetime thermometry is presented, the features of the detection method and the choice of temperature sensor are discussed, and it is demonstrated how the temperature monitoring system was integrated within the viewing system of the endstation used for the visualization of protein crystals. The thermometry system was characterized using a Bi4Ge3O12 crystal scintillator that exhibits good responsivity of the decay time constant as a function of temperature over a wide range (8–270 K). The scintillation sensor was calibrated and the uncertainty of the temperature measurements over the primary operation temperature range of the beamline (30–150 K) was assessed to be ±1.6 K. It has been shown that the temperature of the sample holder, measured using the luminescence sensor, agrees well with the expected value. The technique was applied to characterize the thermal performance of different sample mounts that have been used in MX experiments at the I23 beamline. The thickness of the mount is shown to have the greatest impact upon the temperature distribution across the sample mount. Altogether, these tests and findings demonstrate the usefulness of the thermometry system in highlighting the challenges that remain to be addressed for the in-vacuum MX experiment to become a reliable and indispensable tool for structural biology.