Negative staining permits 4.0 Å resolution with low-dose electron diffraction of catalase crystals

Low-dose electron diffraction of thin single crystals of catalase that are negatively stained with the light-atom compound, dipotassium glucose-1,6-diphosphate, reveals Bragg reflections extending to 4.0 Angstrom (= 0.40 nm). Under the same conditions, negative staining with the traditional heavy-metal salt, ammonium molybdate, also gives diffraction spots extending to 4.0 Angstrom. These results establish that negative staining of protein crystals preserves periodic structural information into the high-resolution range, unlike the widely accepted current belief that this methodology can give a resolution limited to only 20-25 Angstrom. (C) 2001 Elsevier Science B.V. All rights reserved.