• This product was discontinued on 01/01/2013
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CBG-NH2 is an amine-terminated building block particularly suited for the one-step modification of carboxylic ester modified surfaces such as Biacore® CM5 sensor chips. This building block enables you to covalently modify a surface of your choice with SNAP-tag® substrate allowing directed and covalent immobilization of SNAP-tag fusion proteins. 

The SNAP-tag protein labeling system enables the specific, covalent attachment of virtually any molecule to a protein of interest. The SNAP-tag is a protein based on human O6-alkylguanine-DNA-alkyltransferase (hAGT). SNAP-tag substrates are fluorophores, biotin or beads conjugated to guanine or chloropyrimidine leaving groups via a benzyl linker. In the labeling reaction, the substituted benzyl group of the substrate is covalently attached to the SNAP-tag. 

There are two steps to using this system: cloning and expression of the protein of interest as a SNAP-tag fusion, and labeling of the fusion with the SNAP-tag substrate of choice. Expression of SNAP-tag fusion proteins is described in the documentation supplied with SNAP-tag plasmids. The labeling of fusion proteins with the SNAP-tag substrate is described in this document.
Figure 1. Structure of CBG-NH2 (MW 342.4 g/mol)

Properties and Usage

Storage Temperature



  1. Storage: Dry CBG-NH2 should be stored at -20°C.
  2. CBG-NH2 should be dissolved in anhydrous N,N-dimethylformamide (DMF). Choose a solvent volume that will be compatible with the final use. Note that CBG-NH2 is sparingly soluble in DMF. Heating at 37°C, vortexing and/or sonication will aid dissolution. Some remaining precipitation is expected and should be carried forward to the reaction. Remaining solids will continue to dissolve as the coupling reaction proceeds.
  3. Unused CBG-NH2 substrate dissolved in DMF should be stored at -20°C under argon.
  4. Use with Biacore® CM5 Chips
    Surfaces such as Biacore® CM5 chips can be modified with CBG-NH2 so that they will covalently immobilize SNAP-tag fusion proteins.  Surface activation is done using standard amino-coupling procedures (such as exposure to NHS and EDC). Refer to Biacore® CM5 Chips manufacturer's protocols for detailed instructions.


  1. Kindermann, M. et al. (2003). JACS. 125, 7810-7811.


  1. Cellular Imaging and Analysis FAQs


  1. Protocol for Labeling SNAP-tag Fusion Proteins with BG-substrates (S9149)
  2. Reaction Conditions for Chemical Immobilization (S9149)

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Quality Control

Quality Control Assays

The following Quality Control Tests are performed on each new lot and meet the specifications designated for the product. Individual lot data can be found on the Product Summary Sheet/Datacard or Manual which can be found in the Supporting Documents section of this page. Further information regarding NEB product quality can be found here.
  • Physical Purity (HPLC):
    The purity of the product is determined by HPLC analysis.

Safety Data Sheet

The following is a list of Safety Data Sheet (SDS) that apply to this product to help you use it safely.