液相生物电子显微镜:许多已发表的结果和声称的好处是幻想,而不是事实
Robert M Glaeser1, Ravi R Sonani2, Edward H Egelman2
1Department of Molecular and Cell Biology, University of California, 16 Barker Hall #3206, Berkeley, CA 94720, USA.
概括
液相电子显微镜由于辐射损伤和布朗运动而面临分辨率限制. 分析显示,以前声称的GroEL液相图像实际上是空气干燥和负染色.
科学领域:
- 结构生物学是结构生物学.
- 生物物理学的生物物理.
- 电子显微镜的电子显微镜
背景情况:
- 通过电子显微镜 (EM) 绘制液态生物分子的图像是观察动态过程的理想选择.
- 高分辨率成像受到辐射激活分子功能的挑战,以及悬浮粒子的布朗运动.
- 之前的研究声称纳米分辨率液相EM的宏分子复合体,但这些说法在这里重新评估.
研究的目的:
- 批判性地评估高分辨率电子显微镜的可行性,对生物分子在其原生液态阶段.
- 调查之前发表的GroEL液相电磁图像中对比度逆转的原因.
- 为了确定声称的液态电磁图像是否准确地代表了水合状态中的分子.
主要方法:
- 对GroEL的公开电子显微镜图像的分析.
- 图像特征与液相与空气干燥和染色样品的预期结果的比较.
- 在电子显微镜中对比机制的评估,考虑到水,冰和盐的电子散射.
主要成果:
- 公开的GroEL的EM图像,据称来自液态阶段,显示空气干燥的明显迹象.
- 观察到的对比率逆转不是由于水的散射,而是与负染色相一致,可能来自缓冲盐.
- 布朗运动和辐射损伤从根本上限制了在真实液相EM中可实现的分辨率.
结论:
- 由于物理限制,目前无法在自由悬浮的液相中实现生物宏分子的高分辨率电磁成像.
- 重新分析关键的公布数据表明,之前报告的液相电磁图像是样品准备的工件,特别是空气干燥和负染色.
- 需要进一步的方法进步来克服辐射损伤和运动模糊,以实现高分辨率的真实现场液相电磁波.
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