DETERMINATION OF AVIDIN AND BIOTIN BY FLUORESCENCE POLARIZATION

Assays for avidin and biotin are presented which combine high sensitivity with short assay times. Minimum detectable concentrations are 5 ng/mL avidin and 100 pg/mL biotin and assay time is under 10 min. The fluorescence polarization of a biotin-fluorescein conjugate is monitored. Polarization varies as a function of avidin concentration and, at fixed avidin levels, as a function of competing biotin concentrations. This simple, rapid assay has a detection limit about 1000-fold lower than the commonly used 4-hydroxyazobenzene-2-carboxylic acid dye binding method.