Fluorescein biotin (5-((N-(5-(N-(6-(Biotinoyl)amino)hexanoyl)amino)pentyl)thioureidyl) fluorescein) can be used to detect and quantify biotin binding sites and the degree of biotinylation of proteins. Also see biotin-rhodamine 110, biotin-4-fluorescein, and CF® Dye Biotin conjugates.    &lamba;Ex/&lamba; Em= 494/518 nm  Yellow solid soluble in DMSO, or DMF  Store at -20°C and protect from light  C42H50N6O8S2  MW: 831  [134759-22-1]