TALON® Superflow consists of highly cross-linked agarose beads with an immobilized chelating group precharged with Co2+ ions.
The medium binds polyhistidine-tagged proteins with high selectivity and exhibits a reduced affinity for host proteins, giving lower background compared with other IMAC media. The medium is compatible with many aqueous buffers, denaturants, and a range of other additives (Appendix 1, Characteristics of Ni Sepharose, Ni Sepharose excel, TALON® Superflow, and uncharged IMAC Sepharose products). Avoid using DTT (dithiothreitol), DTE (dithioerythritol), and TCEP (TRIS (2-carboxyethyl) phosphine) with TALON® Superflow products. Protein binding capacity will decrease rapidly if used. The medium is suitable for batch purification, and can also be used for packing into liquid chromatography columns such as Tricorn or XK columns. The medium usually works well with protocols designed for Ni2+-based IMAC columns.
Figure 3.37.TALON® Superflow allows for protein purification under native or denaturing conditions and can be used with prokaryotic and eukaryotic expression systems. TALON® Superflow is available in 10 and 50 ml volumes.
This sample preparation procedure is applicable for all formats containing TALON® Superflow. See Cell lysis earlier in this chapter for a general description.
Adjust the sample to the composition and pH of the binding buffer by adding buffer, NaCl, imidazole, and additives from concentrated stock solutions; by diluting the sample with binding buffer; or by buffer exchange.
Pass the sample through a 0.22 µm or a 0.45 µm filter and/or centrifuge it immediately before sample application. Filtration is not necessary when using HiTrap TALON® crude and His GraviTrap. If the sample is too viscous, dilute it with binding buffer; increase lysis treatment (sonication, homogenization); or add DNase/RNase to reduce the size of nucleic acid fragments.
Water and chemicals used for buffer preparation should be of high purity. Filter buffers through a 0.45 µm filter before use. Use high-purity imidazole, which gives essentially no absorbance at 280 nm.
Nonspecific binding of proteins due to electrostatic interactions can be decreased by increasing the NaCl concentration up to 500 mM.
The imidazole concentration required for wash and elution is protein dependent. Chapter 4 (Optimizing purification of histidine-tagged proteins) for further information.
TALON® Superflow is supplied preswollen in 20% ethanol. Prepare a slurry by decanting the 20% ethanol solution and replacing it with distilled water in a ratio of 75% settled medium to 25% distilled water.
For subsequent chromatography procedures, do not exceed 75% of the packing flow rate.
For subsequent chromatography procedures, do not exceed 75% of the packing flow rate.
Purification
Purification procedure for a packed column
In some cases, a blank run is recommended before final equilibration/ sample application. See below for blank run.
Blank run:
Leakage of Co2+ from TALON® Superflow is low under all normal conditions. For very critical applications, leakage during purification can be even further reduced by performing a blank run before loading sample.
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