HIS Lite™ Cy3B Tris NTA-Ni Complex

• Specific labeling of His-tagged proteins – Utilizes Ni(II)-Tris-NTA coordination for site-selective, non-covalent interaction with polyhistidine sequences.
• High binding affinity – Tris-NTA architecture enhances stability, yielding dissociation constants in the nanomolar to picomolar range.
• Reversible and mild conditions – Maintains native protein conformation and function without covalent modification.
• Photostable Cy3B fluorophore – Delivers high quantum yield and resistance to photobleaching for consistent signal intensity.
• Compatible with advanced imaging – Optimized for SMLM, TIRF, FRET, and other fluorescence-based microscopy techniques.

HIS Lite™ Cy3B Tris NTA-Ni Complex is a site-specific, non-covalent labeling reagent designed for the efficient detection of polyhistidine-tagged (His-tagged) proteins in cells, solution, and solid surfaces. The reagent consists of a Tris-nitrilotriacetic acid (Tris-NTA) chelator coordinated with Ni(II) and conjugated to the Cy3B fluorophore. This configuration enables high-affinity binding to His-tags under native conditions without requiring chemical modification of the target protein.

The Tris-NTA moiety offers enhanced binding stability compared to mono- or bis-NTA analogs due to its multivalent coordination with Ni(II), yielding dissociation constants in the nanomolar to picomolar range depending on the His-tag configuration. Binding is rapid, reversible, and specific, allowing for efficient labeling while preserving protein structure and function.

Cy3B is a sulfonated cyanine dye characterized by high quantum yield, minimal triplet-state formation, and excellent photostability. It exhibits excitation and emission maxima at approximately 560 nm and 571 nm, respectively. These optical properties make Cy3B well suited for high-sensitivity imaging applications, including single-molecule localization microscopy (SMLM), total internal reflection fluorescence (TIRF) microscopy, and fluorescence resonance energy transfer (FRET) assays.