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  • SNAP-tag® Purified Protein


    The SNAP-tag is a novel tool for protein research, allowing the specific, covalent attachment of virtually any molecule to a protein of interest. The SNAP-tag is a small protein based on mammalian O6-alkylguanine-DNA-alkyltransferase (AGT). SNAP-tag substrates are derivatives of benzylpurines and benzylchloropyrimidines. In the labeling reaction, the substituted benzyl group of the substrate is covalently attached to the SNAP-tag.

    SNAP-tag Purified Protein can be used as a positive control for in vitro labeling with various SNAP-tag fluorescent substrates. The coding sequence of SNAP-tag was cloned into a pTXB1 derived E. coli T7 expression vector. SNAP-tag protein (MW: 19,694) was expressed and purified according to the instructions in the IMPACT™ kit manual (NEB #E6901). The purified SNAP-tag protein was dialyzed into 1X phosphate buffered saline (PBS) solution containing 1 mM DTT at 1 mg/ml (50 μM) and stored at -80°C.

    Mass spectrometry analysis indicates the SNAP-tag purified protein has two species with molecular weights of 19,694 and 19,829 (with a C-terminal DTT moiety attached).


    Fluorescent in-gel detection of SNAP-tag labeled with SNAP-Vista Green. Various amounts of SNAP-tag were incubated with SNAP-Vista Green at 37°C for 30 min. The protein samples were electrophoresed on a 10–20% Tris-glycine polyacrylamide gel under denaturing conditions. The gel was imaged with Typhoon 9400 at 300V PMT with the 488/526 nm excitation/emission filter set. Lane 1, 6.25 ng; lane 2, 12.5 ng; lane 3, 25 ng; lane 4, 50 ng; lane 5, 100 ng.

    Properties and Usage

    Storage Temperature


    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.
    • In Vitro Protein Labeling:

      The product is tested in an in vitro protein labeling reaction. After incubation the labeled product is visualized on SDS-PAGE by fluorescent detection and verified by mass spectrometry.


    1. Storage: The SNAP-tag Purified Protein may be stored at -20°C for short term use, but should be kept at -80°C for long term storage. SNAP-tag Purified Protein is supplied at a concentration of 50 μM and is supplied in 1X PBS with 1mM DTT. Thaw and aliquot just before use.
    2. Fresh DTT should be added before use each time.

    Supporting Documents

    Material Safety Datasheets

    The following is a list of Material Safety Data Sheets (MSDS) that apply to this product to help you use it safely. The following file naming structure is used to name these document files: [Product Name] MSDS. For international versions please contact us at info@neb.com.


    The Product Summary Sheet, or Data Card, includes details for how to use the product, as well as details of its formulation and quality controls. The following file naming structure is used to name the majority of these document files: [Catalog Number]Datasheet-Lot[Lot Number]. For those product lots not listed below, please contact NEB at info@neb.com or fill out the Technical Support Form for appropriate document.
    1. Cellular Imaging and Analysis FAQs
    1. Labeling SNAP-tag Purified Protein In Vitro (P9312)
    2. View the video "Fluorescent Labeling of COS-7 Expressing SNAP-tag Fusion Proteins for Live Cell Imaging" in the Journal of Visualized Experiments (JoVE)