• This product was discontinued on 01/01/2013
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BG-GLA is a general purpose building block for the synthesis of SNAP-tag® substrates. BG-GLA requires activation before coupling to another functional group such as amine containing precursors including proteins, peptides or oligonucleotides. This building block allows you to make custom SNAP-tag substrates for labeling 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: sub-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 the fusion proteins with the SNAP-tag substrate is described in this document.
Figure 1. Structure of BC-PEG-NH2 (MW 448.5 g/mol)


  1. Dry SNAP-tag building block substrate should be stored at -20°C.
  2. BG-GLA should be dissolved in ahnhydrous N,N-dimethylformamide (DMF) for use. BG-GLA is sparingly soluble in ahnhydrous DMF. Heating at 37°C, vorteing and/or sonication will aid dissolution. Some remaining recipitate is expected and should be carried forward to the reaction. Remaining solids will continue to dissolve as the coupling reaction proceeds. Choose a solvent volume that will be compatible with the final use. Unused BG-GLA substrate dissolved in DMF should be stored at -20°C.


  1. Montalbetti, C:A.G.N., Falque, V. (2005). Tetrahedron. 61, 10827.


  1. Cellular Imaging and Analysis FAQs


  1. Reaction Conditions for Chemical Coupling (S9155)
  2. Labeling SNAP-tag Fusion Proteins with BG-substrates (S9155)

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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.