Compressibility of lysozyme protein crystals by X-ray diffraction

Single-crystal high-pressure X-ray diffraction studies on the protein crystals of orthorhombic and tetragonal hen egg-white lysozyme polymorphs were carried out using a Merrill-Bassett diamond-anvil cell, image-plate detector and synchrotron radiation. The orthorhombic crystal has been squeezed to 85.5% of its ambient pressure volume at about 1.0 GPa; the crystal compresses anisotropically, and neither a glass transition or denaturation was observed. The tetragonal polymorph of lysozyme undergoes amorphization at pressures about 0.2 GPa.