Electron diffraction from single, fully-hydrated, ox-liver catalase microcrystals

High-resolution single-crystal electron diffraction intensity data from fully hydrated, flat, rectangular catalase microcrystals are subjected to various tests which support the thesis that diffraction from crystals with thicknesses up to at least 1500 Å may be treated by the kinematical theory. The ratio of the total diffracted intensity to the incident beam intensity is found to be 0.06 for a 530 Å thick crystal and 0.16 for a 1500 Å thick crystal. A plot of averaged electron-diffraction intensities vs. sin θ/λ also closely resembles molecular-transform-modulated plots of X-ray diffraction intensity data from protein crystals.