Electron beam coater for reduction of charging in ice-embedded biological specimens using Ti(88)Si(12) alloy.
Biological macromolecules embedded in vitreous ice are known to suffer from charging while being imaged in an electron transmission cryomicroscope. We developed an electron beam coater that deposits conductive films onto the surface of frozen-hydrated specimens. The conductive films help to dissipate charge during electron irradiation of poorly conductive ice-embedded biological samples. We observed significant reduction in charging of ice-embedded catalase crystals suspended over holes in a holey carbon film after coating them with a 30-A-thick layer of an amorphous alloy, Ti(88)Si(12). Images of the crystals after coating showed diffraction spots of up to 3 A resolution.
Sherman
Michael B
MB
National Center for Macromolecular Imaging, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030, USA.
Chiu
Wah
W
D000497:Alloys; D002374:Catalase / Q000737:chemistry* / Q000648:ultrastructure; D003460:Crystallization; D007053:Ice; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008854:Microscopy, Electron / Q000379:methods; D015203:Reproducibility of Results; D012825:Silicon; D014025:Titanium; D014961:X-Ray Diffraction / Q000379:methods
D000497:Alloys; D007053:Ice; D014025:Titanium; D002374:Catalase; D012825:Silicon