SNAP-Cell® Fluorescein is a green fluorescent substrate that can be used to label SNAP-tag® fusion proteins inside living cells or in vitro.
This cell-permeable substrate (BG-Fluorescein) is based on diacetylfluorescein and is suitable for standard fluorescein filter sets. Diacetylfuorescein is essentially non-fluorescent, but it becomes fluorescent inside the cell when it is hydrolyzed by non-specific esterases, yielding fluorescein. It has an excitation maximum at 500 nm and an emission maximum at 532 nm. This substrate has limited photostability. If this presents a problem, we recommend using SNAP-Cell 505, which has similar spectral characteristics but much greater photostability. This package contains 50 nmol of SNAP-Cell Fluorescein substrate, sufficient to make 10 ml of a 5 µM SNAP-tag fusion protein labeling solution.