Global analysis of kinetic and stationary diffusion-mediated fluorescence quenching data

The recovery of the Smoluchowski-Collins -Kimball (SCK) model parameters from simulated kinetic and stationary diffusion-mediated fluorescence quenching data is studied. A Levenberg-Marquardt least-squares optimization routine was used for the estimation of the sum of the diffusion coefficients of the fluorophore and quencher, D = D-F* + D-Q, the sum of their radii, R = R-F* + R-Q, and the intrinsic quenching rate coefficient k. Single-curve analysis leads to rather poor parameter estimates. Global, i.e., simultaneous, analysis of quenching decays with different time resolutions (= channel widths) improves the recovery. The best results are obtained when quenching decays are analyzed globally with stationary Stern-Volmer data. The intrinsic quenching rate coefficient k can be recovered when quenching decays are measured with sufficiently high number of counts at a peak channel and analyzed globally with stationary Stern-Volmer data.