Examples of individual fluorescence spectra obtained during end point titrations.

<p>Examples of spectra (A) for construct CTV-TnC (1μM) at 400μM Ca total, excited at various excitation wavelengths (λ_ex; from purple to orange, in order: 400nm, 404nm, 408nm, 410nm, 414nm, 418nm, 420nm, 424nm, 433nm). (B) FRET ratios (F_R, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0164222#pone.0164222.e008" target="_blank">Eq 2</a>) plotted as a function of λ_ex for construct CTV-TnC (1μM), under the 3 conditions tested: initial condition 100μM EDTA (filled circles); next 400μM Ca (as in panel A) (open circles); and lastly 3mM EDTA (filled, inverted triangles). Note that F_R is independent of λ_ex and thus absolute value of acceptor emission intensity, and also that F_R varies reversibly with divalent cation binding.