Density and electron density of aqueous cryoprotectant solutions at cryogenic temperatures for optimized cryoprotection and diffraction contrast.
Density and electron density of aqueous cryoprotectant solutions at cryogenic temperatures for optimized cryoprotection and diffraction contrast.
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DOI：
10.1107/s2059798318003078
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发表时间：
2018-05-01
期刊：
影响因子：
--
通讯作者：
Thorne RE
中科院分区：
文献类型：
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作者：
Tyree TJ;Dan R;Thorne RE
在T = 77 K时测量了8种常用冷冻保护剂水溶液的密度，并用于确定T = 77 K时的电子密度和从室温冷却时的热收缩。 结果为选择冷冻保护剂以优化低温晶体学、低温SAXS、低温X射线成像和基于玻璃化的生物冷冻保存的结果提供了定量依据。在T = 77 K的玻璃相密度的常见的冷冻保护剂（CPA）的水溶液中，甲醇，乙醇，2-丙醇，甘油，2-甲基-2，4-戊二醇（MPD），乙二醇，聚乙二醇200和聚丙二醇425作为CPA浓度的函数进行测量。 体积小至1.65 pl的单个液滴被迅速冷却以实现玻璃相，并且它们在T = 77 K时的密度通过冷冻浮选测定。 这些密度用于确定每种溶液的玻璃相电子密度及其在室温和77 K之间的体积热收缩。 当与实现玻璃相所需的临界冷却速率与CPA浓度的数据相结合时，这些产生冷冻保护剂有效性的替代措施。这些参考数据将有助于最大限度地减少样品应力和机械损伤cryocellulogram，在低温X射线成像和玻璃化为基础的冷冻保存协议，并在最大限度地提高电子密度之间的对比度冷冻保护剂解决方案和生物分子在低温小角度X射线散射实验和冷冻电子显微镜。
The densities of aqueous solutions of eight common cryoprotectants were measured at T = 77 K and were used to determine electron densities at T = 77 K and thermal contractions on cooling from room temperature. The results provide a quantitative basis for choosing cryoprotectants to optimize outcomes in cryocrystallography, cryo-SAXS, cryogenic temperature X-ray imaging and vitrification-based biological cryopreservation. The glass-phase densities at T = 77 K of aqueous solutions of the common cryoprotective agents (CPAs) methanol, ethanol, 2-propanol, glycerol, 2-methyl-2,4-pentanediol (MPD), ethylene glycol, polyethylene glycol 200 and polypropylene glycol 425 were measured as a function of CPA concentration. Individual drops with volumes as small as ∼65 pl were rapidly cooled to achieve the glass phase, and their densities at T = 77 K were determined by cryoflotation. These densities were used to determine the glass-phase electron density of each solution and its volume thermal contraction between room temperature and 77 K. When combined with data for the critical cooling rates required to achieve the glass phase versus CPA concentration, these yield alternative measures of cryoprotectant effectiveness. These reference data will aid in minimizing sample stresses and mechanical damage in cryocrystallography, in cryogenic temperature X-ray imaging and in vitrification-based cryopreservation protocols, and in maximizing electron-density contrast between cryoprotectant solutions and biomolecules in cryogenic temperature small-angle X-ray scattering experiments and cryo-electron microscopy.