Investigation of the Pre-crystallization Stage of Proteinase K in Solution (Influence of Temperature and Precipitant Type) by Small-Angle X-Ray Scattering
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Proteinase K solutions have been investigated by small-angle X-ray scattering in the temperature range of 10–30°C under conditions of tetragonal crystal growth. Addition of ammonium sulfate or sodium nitrate as precipitants is shown to induce the formation of a significant fraction of protein dimers in solution (the dimer content in solution increases only slightly with a decrease in temperature). The structures of possible dimers, which form the pre-crystallization phase in solution (which is necessary for the growth of proteinase K crystals), have been investigated by analyzing the known crystal structure.
We are grateful to V.R. Samygina (Federal Scientific Research Centre “Crystallography and Photonics,” Russian Academy of Sciences) for valuable recommendations and to A.G. Kulikov (Federal Scientific Research Centre “Crystallography and Photonics,” Russian Academy of Sciences) for the help in carrying out the XRD analysis.
The study was performed using equipment of the Shared Research Center of the Federal Scientific Research Centre “Crystallography and Photonics,” Russian Academy of Sciences, and supported in part by the Federal Agency for Scientific Organizations (contract no. 007-ГЗ/Ч3363/26) and the Russian Foundation for Basic Research, project nos. 16-29-14053 ofi_m and 16-32-60144 mol_a_dk.