SNAP-Cell® 505-Star is a photostable green fluorescent substrate that can be used to label SNAP-tag® fusion proteins inside living cells, on cell surfaces, or in vitro. This cell-permeable substrate (CP-6-505) is based on the single isomer 6-carboxyrhodamine 110 and is suitable for standard fluorescein filter sets. It has an excitation maximum at 504 nm and an emission maximum at 532 nm. This package contains 50 nmol of SNAP-Cell 505-Star substrate, sufficient to make 10 ml of a 5 µM SNAP-tag fusion protein labeling solution.
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 arefluorophores, 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: subcloning 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 below.
Figure 1: Live U-2 OS cells stably transfected with pSNAPf-H2B
Cells were labeled with SNAP-Cell 505-Star (green) for 15 minutes at 37°C, 5% CO2.Figure 2: Excitation (dotted line) and emission spectra of SNAP-Cell 505-Star coupled to SNAP-tag in buffer at pH 7.5
Figure 3. Structure of SNAP-Cell 505-Star (MW 621.0 g/mol).
Notes:
Storage: SNAP-Cell 505-Star should be stored at -20°C (long term) or at 4°C in the dark (short term, less than 4 weeks). Protect the substrate from light and moisture. With proper storage at -20°C the substrate should be stable for at least three years dry or 3 months dissolved in DMSO.
