Chloroalkane–modified sensor chips
XanTec’s HOP, HOHC, and HOD sensor chips are coated with either a bioinert 2D carboxylate (HOP) or a 3D polycarboxylate hydrogel (HOHC, HOD), each derivatized with short-chain chloroalkanes. These functional groups form stable covalent bonds with fusion proteins bearing a 33 kDa Halo tag. Reaction is rapid, highly specific, and occurs spontaneously under preconcentration conditions, ensuring uniform ligand orientation on the sensor surface.
Compared to conventional non-selective methods such as EDC/NHS activation, the Halo tag immobilization process offers substantial advantages. It is not only significantly more convenient, but also allows for a more controlled and well-defined immobilization. By avoiding random ligand orientation and ligand crosslinking, which often occur with EDC/NHS coupling, this approach results in a homogeneous ligand population, ultimately leading to improved data quality and reproducibility in kinetic and affinity assays. Consequently, experimental workflows are streamlined, requiring fewer optimization steps, while the consistency and integrity of kinetic interaction analyses are enhanced, making it easier to draw reliable conclusions about binding kinetics and affinities.
Adequate electrostatic preconcentration remains essential for successful protein immobilization. However, traditional preconcentration scouting cannot be performed because Halo-tagged fusion proteins would directly bind to the sensor chip. Therefore, preconcentration and immobilization must be evaluated simultaneously or on a separate non-derivatized sensor chip. For further details, please refer to the product manual.
Key features:
- Faster assay development: No chemical activation required for covalent coupling. Ligand immobilization occurs directly under preconcentration conditions with adjustable ligand density, enabling rapid and reproducible assay setup.
- Exceptional stability: Covalent coupling of Halo-tagged protein results in drift-free, permanently immobilized ligands.
- Oriented immobilization: Site-directed attachment ensures maximum ligand activity.
- Versatile capture capacity: Available on CMDP, CMD, and HC base coatings, offering different immobilization densities for specific experimental requirements.
| Product code | HOP | HOD200M | HOHC200M |
|---|---|---|---|
| Base coating | 2D, ultra-short CM-dextran (high density) |
3D, 200 nm bioinert CM-dextran (medium density) |
3D, 200 nm bioinert polycarboxylate (medium density) |
| Immobilization capacity [µRIU] 2 | ≈ 3,000 | ≈12,000 | ≈15,000 |
| Recommended ligands | Halo-tagged peptides and proteins | ||
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1 All illustrations are schematic representations and are not drawn to scale; dimensions, densities, and spatial relationships do not reflect actual physical or chemical proportions.
2 Based on specific binding of 30 µg/mL HaloTag®-GST fusion protein (61 kDa) in 5 mM sodium acetate pH 5.0, with 1 µRIU corresponding approximately to 1 RU.