An evaluation of adhesive sample holders for advanced crystallographic experiments.
An evaluation of adhesive sample holders for advanced crystallographic experiments.
复制标题
DOI：
10.1107/s1399004714014370
复制
发表时间：
2014-09
期刊：
影响因子：
--
通讯作者：
Sorensen T
中科院分区：
文献类型：
--
作者：
Mazzorana M;Sanchez-Weatherby J;Sandy J;Lobley CM;Sorensen T
在进行复杂的大分子晶体学实验时，已经对市售粘合剂进行了晶体安装评估。本文评估了它们作为高级样品安装和冷冻保护工具的用途，并调查了它们在室温数据收集和湿度控制研究中的适用性。大分子晶体的水合状态经常影响它们的整体顺序，并最终影响它们产生的x射线衍射图案的质量。改变晶体中溶剂含量的后结晶技术可能会引起组成晶体的三维阵列内的重排，从而可能导致更有序的堆积。晶体的水化状态可以通过将其暴露在控制相对湿度的空气流中来控制，在空气流中晶体可以达到平衡。这种方法提供了一种探索晶体水化空间以评估现有晶体衍射能力的方法。这些实验的一个关键要求是将晶体直接暴露在脱水环境中，使其周围残留的母液量最小。这通常是通过将晶体放置在一个平坦的多孔支架（卡普顿网）上，并通过排芯去除多余的液体来实现的。在这里，考虑了一种替代方法，即使用粘合剂直接从结晶滴中捕获裸晶体，将过程减少到一步程序。介绍了使用粘合剂来简化不同类型晶体的收获的影响，以及它们对背景散射的贡献和它们在脱水实验中的用处。结果表明，粘接支架是一种有价值的工具，可用于安装用于湿度控制实验的大分子晶体，并提高衍射实验中的信噪比，并讨论了它们如何保护晶体免受样品环境中的修饰。
Commercially available adhesives have been evaluated for crystal mounting when undertaking complex macromolecular crystallography experiments. Here, their use as tools for advanced sample mounting and cryoprotection is assessed and their suitability for room-temperature data-collection and humidity-controlled studies is investigated. The hydration state of macromolecular crystals often affects their overall order and, ultimately, the quality of the X-ray diffraction pattern that they produce. Post-crystallization techniques that alter the solvent content of a crystal may induce rearrangement within the three-dimensional array making up the crystal, possibly resulting in more ordered packing. The hydration state of a crystal can be manipulated by exposing it to a stream of air at controlled relative humidity in which the crystal can equilibrate. This approach provides a way of exploring crystal hydration space to assess the diffraction capabilities of existing crystals. A key requirement of these experiments is to expose the crystal directly to the dehydrating environment by having the minimum amount of residual mother liquor around it. This is usually achieved by placing the crystal on a flat porous support (Kapton mesh) and removing excess liquid by wicking. Here, an alternative approach is considered whereby crystals are harvested using adhesives that capture naked crystals directly from their crystallization drop, reducing the process to a one-step procedure. The impact of using adhesives to ease the harvesting of different types of crystals is presented together with their contribution to background scattering and their usefulness in dehydration experiments. It is concluded that adhesive supports represent a valuable tool for mounting macromolecular crystals to be used in humidity-controlled experiments and to improve signal-to-noise ratios in diffraction experiments, and how they can protect crystals from modifications in the sample environment is discussed.