SPY555-BG is the benzylguanine derivative of SPY555 fluorophore. It emits light in the orange part of the UV-ViS spectrum, it is fluorogenic, highly cell permeable and well suited for STED and SIM superresolution imaging. SPY555-BG can be imaged with a standard Cy3 filterset. It can be used for widefield, confocal, SIM or STED imaging in living or fixed cells and tissue. It has the same structure as MaP555-SNAP the name used in its original publication in Nature Chemistry. SPY555-BG is an alternative to SNAP-Cell®* TMR-Star, it has faster labeling kinetics. Benzylguanine (BG) is the substrate of the self labeling tag SNAP-tag™*. Upon reaction with a BG derivative, SNAP-tag™* forms a covalent bond with the substrate and releases guanine. It allows to permanently attach a fluorescent label to any protein of interest (POI) expressed as SNAP-tag™* fusion. *SNAP-tag™ and SNAP-Cell® are registered trademarks of New England Biolabs, Inc.
