The use of low temperature X‐ray diffraction to evaluate freezing methods used in freeze‐fracture electron microscopy
The use of low temperature X‐ray diffraction to evaluate freezing methods used in freeze‐fracture electron microscopy
复制标题
使用低温 X 射线衍射评估冷冻断裂电子显微镜中使用的冷冻方法
作者：
T. Gulik;M. Costello
用X射线衍射法和脂质-水模型体系的冷冻断裂结果比较了冷冻断口电子显微镜的两种冷冻方法。研究了含16%水的卵磷脂和含55%水的卵磷脂-磷脂酰肌醇在接近其熔化温度(113K)的氟里昂-22液体中冷冻淬火时，碳氢链的分子结构和冰晶形成程度的扰动。夹在由电子显微镜栅格隔开的铜片之间的非常薄的样品比包含在传统的Balzz型金片岩中的小样品显示出更少的冻结引起的结构重排。这些结果表明，在非常薄的制备物中的冻结速度比在常规制备物中的冻结速度更快，这可能部分是由于导电性差的样品通过高导电性的铜片改善了热的散失。
Two methods of freezing samples for freeze‐fracture electron microscopy have been compared using X‐ray diffraction and freeze‐fracture results from lipid‐water model systems. Perturbations of the molecular organization of hydrocarbon chains and the extent of ice crystal formation have been evaluated for lamellar phases of egg lecithin containing 16% water and egg lecithin‐phosphatidylinositol containing 55% water, both freeze‐quenched in liquid Freon‐22 near its melting temperature (113 K). Very thin samples sandwiched between copper sheets separated by an electron microscope grid show much less freezing induced structural rearrangement than small samples contained on conventional Balzers‐type gold planchettes. These results show that the rate of freezing in the very thin preparations is greater than in the conventional ones, which is probably due in part to the improved dissipation of heat from a poorly conductive sample through highly conductive copper sheets.