Representative fluorescence polarization of Rv1219c. The binding isotherm of Rv1219c with safranin O, showing a KD of 42.4 ± 7.6 μM. Fluorescence polarization is defined by the equation, FP = (V − H)/(V + H), where FP equals polarization, V equals the vertical component of the emitted light, and H equals the horizontal component of the emitted light of a fluorophore when excited by vertical plane polarized light. FP is a dimensionless entity and is not dependent on the intensity of the emitted light or on the concentration of the fluorophore. mP is related to FP, where 1 mP equals one thousandth of a FP.