Plotting the FRET fraction versus intensity of these grouped pixels revealed a clear trend ( Figure 3B , black dots), which was well fitted by Eq. 7 ( Figure 3B , dashed line), with best-fit values of P f = 0.123 ± 0.006 and , where α , the relative brightness of donors engaged in FRET to those not engaged in FRET, was previously estimated by the ratio of lifetimes as 0.45.
1
—
—