Cy5 Biotin can be used for detecting and quantifying biotin binding sites of avidin, streptavidin or neutravidin. This reagent overcomes major shortcomings of commonly used Biotin-4-fluorescein – poor solubility in aqueous media and pH dependent absorbance and emission. Cy5 Biotin is a water soluble reagent and its red fluorescence is pH independent from pH 4 to pH 10. A flexible PEG3 spacer between biotin moiety and fluorescent tag minimize steric hindrance involved in binding to avidin, streptavidin or neutravidin.
