CAJ | 학술논문

液氮和液氦在低温电子显微镜中都可以作为冷冻剂来保持样品处于含水冷冻状态.本文分析了收集于一台300千伏的日本电子(JEOL)低温电镜和样品处于液氦温度4 K的两组生物大分子单颗粒数据:第一组为噬菌体epsilon 15的数据,成像于Gatan 4 k×4 k电荷耦合器件;第二组是记录在Kodak SO-163底片上的噬菌体P22的数据.对这两组数据的频谱分析显示这些数据的信号分辨率均可达5～6埃.并用实验B因子对这两组数据的质量进行了定量分析.本文结果显示液氦冷冻电镜可用来收集单颗粒生物大分子的高分辨三维结构重构所需的数据.
액담화액양재저온전자현미경중도가이작위냉동제래보지양품처우함수냉동상태.본문분석료수집우일태300천복적일본전자(JEOL)저온전경화양품처우액양온도4 K적량조생물대분자단과립수거:제일조위서균체epsilon 15적수거,성상우Gatan 4 k×4 k전하우합기건;제이조시기록재Kodak SO-163저편상적서균체P22적수거.대저량조수거적빈보분석현시저사수거적신호분변솔균가체5～6애.병용실험B인자대저량조수거적질량진행료정량분석.본문결과현시액양냉동전경가용래수집단과립생물대분자적고분변삼유결구중구소수적수거.
Both liquid nitrogen and liquid helium can be used as cryogens to keep biological specimens in their frozen hydrated state in an electron cryomicroscope. Here we have analyzed two sets of biological single-particle image data collected in a JEOL 300-kV electron cryomicroscope with the specimens kept at liquid helium temperature 4 K. The first dataset was the epsilon 15 bacteriophage recorded on a Gatan Ultrascan 4 k × 4 k charged-coupled device (CCD). The second dataset was the P22 bacteriophage recorded on Kodak SO-163 photographic film. Both data contain detectable signal to at least 5 ～ 6 (A) as judged from the incoherently averaged Fourier transform (FT) of the boxed-out particle images. The data quality of both datasets was further quantified by the experimental B-factor, which describes the overall Fourier amplitude decay for the FT of the boxed-out particle images fiom each CCD frame or electron micrograph. These analyses suggest that the liquid helium-cooled electron cryomicroscope can yield single-particle image data suitable for high resolution reconstruction.