Nederlof Igor, Li Yao Wang, van Heel Marin, Abrahams Jan Pieter
Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands.
Acta Crystallogr D Biol Crystallogr. 2013 May;69(Pt 5):852-9. doi: 10.1107/S0907444913002734. Epub 2013 Apr 19.
Flash-cooled three-dimensional crystals of the small protein lysozyme with a thickness of the order of 100 nm were imaged by 300 kV cryo-EM on a Falcon direct electron detector. The images were taken close to focus and to the eye appeared devoid of contrast. Fourier transforms of the images revealed the reciprocal lattice up to 3 Å resolution in favourable cases and up to 4 Å resolution for about half the crystals. The reciprocal-lattice spots showed structure, indicating that the ordering of the crystals was not uniform. Data processing revealed details at higher than 2 Å resolution and indicated the presence of multiple mosaic blocks within the crystal which could be separately processed. The prospects for full three-dimensional structure determination by electron imaging of protein three-dimensional nanocrystals are discussed.
用300 kV的低温电子显微镜在Falcon直接电子探测器上对厚度约为100纳米的小蛋白质溶菌酶的快速冷却三维晶体进行成像。这些图像是在接近聚焦的情况下拍摄的，肉眼看起来没有对比度。在有利的情况下，图像的傅里叶变换揭示了高达3埃分辨率的倒易晶格，约一半的晶体可达4埃分辨率。倒易晶格点显示出结构，表明晶体的有序性并不均匀。数据处理揭示了高于2埃分辨率的细节，并表明晶体内存在多个可单独处理的镶嵌块。讨论了通过蛋白质三维纳米晶体的电子成像确定完整三维结构的前景。
