Predicting the Effect of Chemical Factors on the pH of Crystallization Trials

Julie Wilson; Marko Ristic; Jobie Kirkwood; David Hargreaves; Janet Newman

doi:10.1016/j.isci.2020.101219

Predicting the Effect of Chemical Factors on the pH of Crystallization Trials

iScience. 2020 Jun 26;23(6):101219. doi: 10.1016/j.isci.2020.101219. Epub 2020 May 30.

Authors

Julie Wilson¹, Marko Ristic², Jobie Kirkwood³, David Hargreaves⁴, Janet Newman⁵

Affiliations

¹ Department of Mathematics, University of York, York, UK. Electronic address: julie.wilson@york.ac.uk.
² Collaborative Crystallisation Centre, CSIRO, Parkville, VIC, Australia.
³ Department of Chemistry, University of York, York, UK.
⁴ AstraZeneca, Darwin Building, Cambridge Science Park, Cambridge, UK.
⁵ Collaborative Crystallisation Centre, CSIRO, Parkville, VIC, Australia. Electronic address: janet.newman@csiro.au.

Abstract

In macromolecular crystallization, success is often dependent on the pH of the experiment. However, little is known about the pH of reagents used, and it is generally assumed that the pH of the experiment will closely match that of any buffering chemical in the solution. We use a large dataset of experimentally measured solution pH values to show that this assumption can be very wrong and generate a model that can be used to successfully predict the overall solution pH of a crystallization experiment. Furthermore, we investigate the time dependence of the pH of some polyethylene glycol polymers widely used in protein crystallization under different storage conditions.

Keywords: Chemistry; Crystallography; Structural Biology.