Product 6115

qBBr is a low molecular weight, fluorescent probe for labeling thiols. This probe is essentially non-fluorescent until it reacts with a thiol group. The bromomethyl group is relatively selective for reaction with thiols at physiological pH but may also react with carboxylates at pH above 7. Unlike related bimane probes that are readily cell-permeant, the trimethylammonium group inhibits the membrane-permeability of qBBr. This probe is used as a derivatization agent for thiol containing molecules and contains a positive charge that facilitates the separation of conjugates by electrophoresis or ion-exchange chromatography. The conjugates of qBBr are optimally excited near 394 nm and have a variable emission near 490 nm.