BroMotriMethylaMMoniuMbiMane BroMide is a charged fluoresent sulfhydryl active reagent. Bromotrimethylammoniumbimane is a derivative of monobromobimane containing a positive charge which permits separation of its conjugates by electrophoresis or cation-exchange chromatography. The membrane permeability of this charged bimane as well as its ability to access sites within a protein may differ from that of the uncharged bimane probes. These reagents are also useful for detecting the distribution of protein thiols in cells before and after chemical reduction with disulfides. Fluorescence: max. Abs. l = 398nm, max. Em. l = 475-485 (when reacted with thiol); e x 10-3: 5.0