Identification of the Precursor Cluster in the Crystallization Solution of Proteinase K Protein by Molecular Dynamics Methods

It is known that precursor clusters appear in solution prior to protein crystallization. For proteinase K, as it was found by SAXS, such clusters are dimers, but the accuracy of the method did not allow for determining its type. In this work, the behavior of six possible types of precursor clusters was simulated by the molecular dynamics technique. Stability analysis revealed the most probable type of dimer formed in the proteinase K solution before its crystallization. SAXS data modelling also supported the MD calculations. The dynamics of this precursor cluster was modeled at three temperatures: 20, 30, and 40 degrees C. At 40 degrees C, an abnormal increase in the stability of the thermophilic proteinase K was found.