Reproducible improvements in order and diffraction limit of crystals of bovine mitochondrial F₁-ATPase by controlled dehydration

Orthorhombic crystals of bovine F(1)-ATPase have been subjected to controlled dehydration. A decrease in the relative humidity surrounding the crystals to 90% reproducibly reduced their unit-cell volume by 22% (950,000 Angstrom(3)) and improved the diffraction limit and mosaic spread of the crystals significantly. These dehydrated crystals diffracted X-rays to 1.8 Angstrom resolution at a synchrotron source, the best diffraction limit yet attained with these crystals, although radiation damage limited the resolution of a complete data set to 1.95 Angstrom.