In protein crystallization, as well as in many other fields, it is known that the pH at which experiments are performed is often the key factor in the success or failure of the trials. With the trend towards plate-based high-throughput experimental techniques, measuring the pH values of solutions one by one becomes prohibitively time- and reagent-expensive. As part of an HT crystallization facility, a colour-based pH assay that is rapid, uses very little reagent and is suitable for 96-well or higher density plates has been developed.
Supporting information
 | Microsoft Excel (XLSX) file https://doi.org/10.1107/S0907444912018768/be5201sup1.xlsx
Formulations of NPCF_4 screen. Chemical compositions of the 96 crystallisation solutions that make up the NPCF_4 crystallisation screen. This is an in-house screen, similar to commercially available screening kits, developed at CSIRO. The pH as measured with a pH meter and glass electrode is in the third column from the right, the pH as estimated from the dye assay is in the second column from the right, and the pH as given for the buffer component is in the rightmost column. The pH columns have been coloured pink where either the electrode measured or dye-estimated pH varies by more than 2 pH units from the pH of the buffer component of the well. The root-mean-squared average deviation (RMSD) of the difference between the electrode measured and dye estimated pH values for the 96 solutions is 0.29 pH units, the average difference between the two is -0.06 pH units. |
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