Bio-Rad Profinia™ Protein Purification Instrument - Manual (Page 131)

Note: Desalting buffers are already included in native IMAC and GST purification and
buffer kits. Optimized desalting and storage solutions for unique proteins need to be
determined empirically.
The desalting solutions and cartridges can be used to remove or exchange salts, buffers,
and small molecules from any protein sample. Table 10.5 provides a list of buffer
compositions.
The desalting cartridges are provided in water with 0.05% sodium azide as a preservative,
and can be stored between 4 and 22°C prior to use. The cartridges are packed with
10 ml of Bio-Rad P6 size exclusion resin, and typically yield ~80% or more recovery of
applied target protein. The resin in the P6 desalting cartridges interacts minimally with
proteins. When used with the cleaning buffers, different proteins can safely be applied to
the same desalting cartridge.
Table 10.5. Formulations for buffers and solutions provided in the Profinia desalting kits.
Profinia Supplied Concentrated Working 1x Vol, Buffer
Solution Formulation Formulation ml Position
Desalting 5x 685 mM NaCl, 13.5 mM KCl, 137 mM NaCl, 2.7 mM KCl, 200 4
buffer 21.5 mM Na
2
HP0
4
, 4.3 mM Na
2
HP0
4
,
40.5 mM KH
2
P0
4
, pH 7.0 8.1 mM KH
2
P0
4
, pH 7.4
(pH 7.4 upon dilution)
Cleaning 2x 1,000 mM NaCl, 100 mM Tris, 500 mM NaCl, 50 mM Tris, 125 5
solution 1 pH 8.0 pH 8.0
Cleaning 4x 2,000 mM NaCl, 500 mM NaCl, 125 6
solution 2 400 mM NaOAc, pH 4.5 100 mM NaOAc, pH 4.5
Storage 2x 4% C
6
H
5
CH
2
OH (benzyl 2% C
6
H
5
CH
2
OH (benzyl 200 7
solution alcohol) alcohol)
Figure 10.4 shows proper placement of desalting buffers in the Profinia instrument.
Fig. 10.4. Desalting buffers properly positioned with instrument lid closed. Also shown, the desalting loop
installed in the cartridge 1 position.
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