The Monoclonal Anti-His Tag Antibody Europium chelate is a universal tool for TR-FRET assays that can bind His-tagged proteins. This product uses specific anti-His tag antibody covalently conjugated with Eu³⁺ chelate, and it can be used in combination with other Acceptors directly or indirectly labeled with fluorescent dyes. When the Donor and Acceptor come into close proximity (within a distance of less than 10 nm), a FRET reaction occurs: the 620 nm signal emitted by the Donor upon excitation by a specific light source is received by the Acceptor, which then emits a 665 nm signal.