An investigation of the effects of varying pH on protein crystallization screening

Protein crystallization occurs when the solution conditions are suitable for nucleation and growth of the crystals. pH, as one of the most important parameters that governs the protein crystallization process, can affect the conformation, activity, electrostatic interactions and solubility of protein in the solution. Hence, manipulating the pH is an important path to success in crystallizing proteins. In this paper, we show that varying pH levels over the incubation time during the crystallization process can help increase the chance of obtaining protein crystals. The process of varying the pH can be considered as one way to automatically search for a suitable pH for successful crystallization. This discovery can guide us to develop a new screening strategy in which varying the pH against the incubation time is the major process used during the crystallization screening. Our screening experiments verified that varying the pH is indeed a promising method to achieve efficient crystallization screening of a protein.