How Biacore Sensor Chip NTA chelation capture works

Sensor Chip NTA consists of carboxymethylated dextran with covalently immobilized nitrilotriacetic acid (NTA). The NTA molecule chelates metal ions such as nickel (Ni²⁺), creating coordination sites that bind to poly-histidine tags on recombinant proteins and other biomolecules.

The advantages of capture versus covalent immobilization techniques

Non-covalent capture of ligands, for example by metal ion chelation, has a number of advantages over covalent immobilization. Tagged proteins can be captured directly from crude cell extracts or culture medium, requiring little or no sample preparation. Since fresh ligand is captured for each cycle, the same chip surface can be used for analysis interactions involving different ligands. Regeneration conditions are generic and therefore the need for assay development is minimized. In addition, capture generates a directed structural orientation of the protein on the surface, potentially offering optimal site exposure.

Sensor Chip NTA for fragment-based drug discovery (FBDD)

The need for technologies to reliably detect and profile interactions involving very small compounds is increasing in areas such as fragment-based drug discovery (FBDD). Improvements in SPR instrument sensitivity have paved the way for application of chelation capture methods in FBDD.

In contrast to streptavidin capture methods, when Sensor Chip NTA is used for FBDD, target protein can readily be removed from the surface of the chip using a pulse of EDTA. In this way, the target protein is always fresh and will not decay.

Researchers at SGC Karolinska laboratory used Sensor Chip NTA for PARP1 inhibitor screening as part of a successful FBDD program in anticancer drug development. In assays performed using Biacore T200, it was possible for the group to differentiate potential inhibitors of target proteins based on their interaction profiles despite binding to highly similar active sites. In addition, the researchers found that Sensor Chip NTA had the advantage of allowing orientation of the immobilized target protein to be controlled and standardized.

Sensor chip formats for Biacore systems

Biacore sensor chips are available in two formats:

• “S series” sensor chips are for use with Biacore 8K+, Biacore 8K, Biacore T200, Biacore S200, and Biacore 4000 SPR systems.
• Sensor chips not designated with “S series” are designed for Biacore X100, Biacore 3000 and Biacore C SPR systems.