TALON spin columns contain 0.5 ml TALON-nx, an immobilized metal affinity chromatography resin for the purification of recombinant his-tagged proteins under native or denaturing conditions.
TALON His-Tag Purification Resins allow you to prepare exceptionally pure His-Tag proteins from bacterial, mammalian, yeast, and baculovirus-infected cells under native or denaturing conditions. TALON is a cobalt-laced immobilized metal affinity chromatography (IMAC) resin that binds his-tagged proteins with higher specificity than nickel-laced resins. Therefore, TALON resins provide the highest purity of his-tagged proteins. Furthermore, each cobalt ion binds to the resin at four sites, resulting in low metal ion leakage.
The active core contains the highest purity cobalt
TALON metal affinity resins are complexed with cobalt ions, making them highly selective for other labeled proteins. The cobalt-containing reactive core of TALON has strict steric requirements—adjacent histidines can only bind if they contain adjacent histidines or are specifically positioned for proteins. Nickel-based resins (such as Ni-NTA) are less steric - these resins have a higher affinity for randomly positioned (i.e. non-His-tagged) histidines. Therefore, TALON resin binds more specifically to his-tagged proteins.
Uniform matrix ensures less contamination
Cobalt-based resins have a more uniform structure than nickel-based resins. TALON resins contain negatively charged reactive sites that form three-dimensional pockets. Each pocket contains three carboxyl groups and a nitrogen atom, which together bind a positively charged cobalt ion—an arrangement that allows the cobalt ion to bind to two adjacent histidine residues. In this structure, the cobalt is very tightly bound and cannot be leached from the resin. Nickel-based resins are less homogeneous in structure because nickel ions can form two different coordination complexes: one of them forms three-dimensional pockets similar to TALON ligands, and the other forms planar (flat) structures. In the twisted planar structure, each nickel ion is bound to only two carboxyl groups and one nitrogen atom. This planar structure therefore binds the nickel ions less tightly, allowing them to leach out of the resin. TALON metal affinity resins have a homogeneous matrix that provides high-affinity binding under a variety of purification conditions, ensuring optimal protein purification.
TALON spin column
These ready-to-use spin columns contain TALON-NX resin for the simultaneous purification of several his-tagged proteins within 30 minutes. They are recommended for small-scale, one-off applications, such as verification of his-tagged protein expression in transformants, or pilot-scale purification protocols.
Choice of native or denaturing purification conditions
TALON resin maintains its protein binding specificity and yield under a variety of purification conditions. It is stable under both denaturing and native (non-denaturing) conditions. The decision to use native or denaturing purification conditions depends on protein location, solubility, availability of his-tags, downstream applications, and preservation of biological activity.
Local conditions
Purifying proteins under native conditions is the most effective way to maintain their biological activity, but requires the protein to be soluble. Advantages include:
The redenaturation step at the end of purification is eliminated, saving time and preventing significant loss of activity.
Retains the ability to co-purify enzyme subunits, cofactors, and associated proteins.
Denaturation conditions
Because proteins overexpressed in prokaryotic systems sometimes form insoluble aggregates called inclusion bodies, you may need to purify the protein under denaturing conditions - use strong denaturing agents such as 6M guanidine or 8M urea to enhance protein solubility. Advantages include:
Complete solubilization of inclusion bodies and his-tagged proteins.
Improved binding to the matrix and reduced non-specific binding due to full exposure of the His-tag.
His-tagged proteins purified under denaturing conditions can be used directly for subsequent applications, or may require renaturation and refolding. Protein refolding and refolding can be performed prior to elution from the column. However, because urea and guanidine molecules compete with histidine for metal binding, the yield of recombinant protein will be lower than under native conditions.
Use of reducing agent
Purification of TALON resins can be performed in the presence of β-mercaptoethanol instead of DTT or DTE to preserve reduced sulfhydryl (-SH) groups that are important for the biological activity and structure of specific proteins. In the presence of β-mercaptoethanol, the yield of TALON was higher than that of Ni-NTA.