Fig. 5.

Compartmental model of OCP-quenched CB-PB phycobilisome for one and two quenchers. a Schematic structure and connectivity of compartmental CB-PB model, after van Stokkum et al.⁶¹. All components are colored and positioned according to the structure shown in Fig. 1. Eight possible quenching sites for OCP are labeled (a–f, plus a′ and d′). b Scatter plot of brightness vs. fluorescence lifetime simulation results for four model conditions: unquenched (U), C-PC hexamer only (B), one OCP bound at site a, a′, or c (Q₁), or two OCPs bound at site combinations ad, a’d’, or bc (Q₂), with an assumed quenching rate of 540 ns⁻¹ for each OCP compartment. Ellipses show the locations of the 95% confidence intervals for the four experimentally measured states U, B, Q₁, and Q₂, as originally depicted in Fig. 3c. c Brightness and fluorescence lifetime of the CB-PB phycobilisome for the case of one bound quencher located at each of the four rotationally unique sites a, a′, c, and e, plotted for increasing quencher strength. d Brightness and fluorescence lifetime of the CB-PB phycobilisome for two bound quenchers at each of the four unique pairs of C₂-symmetric sites ad, a′d′, bc, and ef, plotted for increasing quencher strength. Horizontal lines in c and d show the experimentally measured parameters for Q₁ (orange) and Q₂ (red)