Performance of a 2k CCD camera designed for electron crystallography at 400 kV

Area of Science:

• Structural Biology
• Biophysics
• Materials Science

Background:

• Charge-coupled device (CCD) cameras are crucial for electron microscopy.
• Previous research focused on general CCD performance in electron microscopy.
• Protein crystallography requires specific camera characteristics due to low signal-to-noise ratios and high dynamic range needs.

Purpose of the Study:

• To assess the performance of a CCD camera optimized for 400 kV electron crystallographic studies of proteins.
• To evaluate the suitability of the camera for low-exposure imaging and high-dynamic-range electron diffraction data collection.
• To compare CCD performance against traditional photographic film.

Main Methods:

• A CCD camera with a P43 scintillator and 24-micron pixels was optimized for 400 kV operation.
• Image binning by a factor of two was employed to address point spread function broadening.
• A large 2048 x 2048 pixel array CCD was used to maintain adequate recording area.
• Performance was evaluated using protein crystals and compared with photographic film.

Main Results:

• The camera provides adequate signal levels for low-exposure protein studies, though resolution is slightly degraded by the thicker scintillator.
• Electron diffraction data collected by the CCD camera demonstrated superior quality compared to photographic film.
• Image quality for low-exposure protein studies was comparable, though not superior, to film.

Conclusions:

• The optimized CCD camera is well-suited for 400 kV electron crystallography, particularly for collecting high-quality electron diffraction data.
• While image quality for low-exposure protein imaging is comparable to film, the CCD offers advantages in diffraction data.
• The findings are applicable to other electron microscopy techniques like single-particle analysis.