Interactions of double-labeled CYP3A4 proteins with testosterone monitored by LRET.

<p>Interactions of C377/C468-DY/ER (circles) and C58/C64/C121-ER/DY (triangles) with testosterone monitored by LRET in steady-state (<i>a</i>) and lifetime (<i>b</i>) setup. Panel <i>a</i> shows the changes in the intensity of donor fluorescence observed in titrations of the double-labeled proteins with testosterone. The lines show the results of fitting of the data sets to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083898#pone.0083898.e004" target="_blank">Eq. 4</a>. Panel <i>b</i> shows the phosphorescence decay traces recorded in the absence of added ligand (open symbols) and in the presence of 100 µM testosterone (closed symbols)