SY-21 DBCO (QSY®-21 equivalent) is a nonfluorescent acceptor dye often used for preparation of peptide and oligonucleotide FRET probes. A broad and intense quenching range from 580 nm to 680 nm makes it useful as an acceptor in fluorescence resonance energy transfer (FRET) applications in conjunction with fluorescent dyes at 580 nm to 680 nm, such as Fluorescein, Alexa Fluor® 568, 594, 633, 647, TAMRA, ROX, Texas Red and Cy5.
SY-21 DBCO reacts with azides via a copper-free “click chemistry” reaction to form a stable triazole and does not require Cu-catalyst or elevated temperatures. In application where the presence of copper is a concern SY-21 DBCO is an ideal alternative to copper requiring fluorescent alkynes.
QSY®-21 is registered trademarks of ThermoFisher Scientific.