For in vitro use only!
Shipping: shipped at ambient temperature
Storage Conditions: store at 8-10 °C
Shelf Life: 12 months
Extended broad range pH-screening independent of the chemical nature of the components of the buffer system.
6 broad range buffer systems, each consisting of a low and a high pH buffer stock (1 M concentration) at 20 ml aliquots.
Choosing the right buffer/pH is vital for the successful performance of a crystallization experiment, where the buffering chemical is usually employed in rather high concentrations, e.g. at 100 mM. The buffer is of particular importance since it adjusts the pH of the protein solution during crystallization and it can also form specific interactions with protein molecules.
For a successful optimization of crystallization conditions it is of advantage to alter independent factors of the crystallization cocktail. An independent broad pH screen (e.g. from pH 4.0 - 10.0) is not possible with conventional individual buffer systems, since their buffering range is usually much smaller. Thus, screening of a broad pH range would require several chemically distinct buffer substances, precluding an independent pH screening.
One way to sample a broad pH range without changing the chemical composition of the buffering component is the application of extended range buffer systems or so-called Super Buffers as arranged in JBScreen pH-2D.
The JBScreen pH-2D
JBScreen pH-2D contains 6 Super Buffer systems, each composed of a mixture of three individual buffers with a distinct chemical nature and well separated pKa-values (Table 1).
Each buffer system is supplied as low and high pH stock solution, which can be mixed at different ratios to obtain different pH values within the range. Plotting the pH vs. the percentage of high pH stock solution in the mixture results in an almost linear pH function for any Super Buffer system in JBScreen pH-2D (see example of CHC buffer in figure 1).
|No.||Buffer composition||Ratio||pH low||pH high|
Sodium dihydrogen Phosphate
|6||Sodium Tartrate dihydrate|
The appropriate low and high pH stock solutions are mixed at different ratios to sample a broad pH range (see example of CHC buffer in figure 1). The 1 M stock solutions have to be diluted in the crystallization experiment, i.e. upon adding precipitant and salt solutions. JBScreen pH-2D can also be incorporated into existing screens, replacing the conventional buffering component.
Furthermore, JBScreen pH-2D is particularly suitable for application with liquid handling robots where number of stock solutions is limited.
 Newman (2004) Novel buffer systems for macromolecular crystallization. Acta Cryst. D 60:610.