Effects of different post-crystallization soaking conditions on the diffraction of Mtcp1 crystals

The crystal structure of human Mtcp1 was determined at 2 Angstrom resolutio n after the X-ray diffraction limit was improved by post-crystallization so aking in 2.0 M ammonium sulfate for 1-5 months. The effects of varying the ammonium sulfate concentration and addition of polyethylene glycol to the s oaking solution were examined in order to understand the phenomenon and to reduce the soaking time. Soaking the crystal for one week in a solution of 1.5 M ammonium sulfate and 2% PEG 3400 gave the desired improvement in diff raction quality. Therefore, different soaking conditions should be explored when crystals show disordered and low-resolution diffraction.