Figure 5.

Fluorescence lifetime measurements on IHF-H’ compared with IHF-H1 (design I constructs). (A) Fluorescence intensity decay traces are shown for H’_DA (black), H1_DA (maroon), and H’_nAt_DA (blue-green), measured in the presence of IHF. Decay traces on DNA_DA in the absence of IHF (red) and DNA_D in presence of IHF (green) are shown for comparison. Measurements were done with 5 μM DNA and 5 μM IHF. The instrument response function (gray) is shown for comparison. (B) The MEM lifetime distributions obtained from the fluorescence decay traces measured for IHF-H’ (black), IHF-H1 (maroon), and IHF-H’_nAt (blue-green) are shown. The amplitudes of the distributions are normalized to add up to one. The average lifetime for the DNA_DA in the absence of IHF (red) and DNA_D in presence of IHF (green) are indicated by the vertical dashed lines.