Investigation of the Pre-crystallization Stage of Proteinase K in Solution (Influence of Temperature and Precipitant Type) by Small-Angle X-Ray Scattering

Resumo

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.