Protein tethering kit (cysteine)


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This kit applies cysteine–maleimide chemistry to attach DNA handles to your protein of interest for subsequent optical-tweezers measurements of protein folding and conformational changes. We recommend this labeling procedure over ybbR labeling, but it requires the absence of native cysteine residues on the protein of interest, especially in the functional domain of the protein.

For labeling, short maleimide-modified oligonucleotides react with specifically incorporated cysteines in the protein. These oligonucleotides then anneal with the complementary 5’-overhangs of two DNA handles.

The kit also includes purified and functionalized adenosine kinase (AdK) that can be used as a positive control and quality assurance for each step of the labeling procedure.

Our Protein tethering kit relieves you from costs and time that are typically required for personnel training, troubleshooting, experiment optimization, and custom application development. After finishing this kit, new materials can easily be ordered as a recurring package.

Estimated for 2 weeks of measurements (handles and beads, more can be ordered as Protein handles kit (recurring))

Estimated for 8 weeks of measurements (labeled protein and control)

Estimated 1-3 weeks delivery time


Maleimide-modified oligonucleotides:

40 μl, 2 vials. Oligonucleotides for protein labeling using maleimide–cysteine chemistry. Store at -80°C.

Biotinylated and digoxigenin-labeled DNA handles (529 bp):

4 μl, 10 vials. Handles mix (50/50) with an overhang complementing the maleimide-modified oligonucleotides. Store at -80°C.

TCEP (10 mM):

5 μl, 2 vials | 10 mM. Reducing agent. Store at -80°C.

6xHis AdK control protein (cysteine):

40 μl | 0.5 μg/μl (20 μM). Store at -80°C.

Streptavidin-coated silica beads (⌀ 1.0–1.4 μm):

25 μl | 1% (w/v). Beads in PBS with 3 mM sodium azide, with a specific diameter (e.g., 1.2 μm) within the given range. Store at +4°C.

Anti-digoxigenin-coated polystyrene beads (⌀ 0.7–0.9 μm):

60 μl | 0.1% (w/v). Beads in PBS with 3 mM sodium azide, with a specific diameter (e.g., 0.8 μm) within the given range. Store at +4°C.

Product Resources

Want to learn more?

See our Protein Folding and Conformational Changes application notes.

Want to use this product in practice?

Find out more about the C-Trap here.

Download the Full Specifications or View the Experimental Protocols