Multi-wavelength fluorescence-quenching model for determination of XXXX conditional stability constants and ligand concentrations of @entity40834 .

@entity13552 @entity3785 @entity8863 @entity21044 @entity9109 @entity40834 @entity920
In this work, a multi-wavelength model (MWM) is developed. It uses fluorescence bands in the @entity40834 (FA) spectrum that quench upon binding of inorganic @entity8863 to FA. Quenching data at pH values of 5, 6, and 7 are placed in sets, containing fluorescence measures at select wavelengths versus added @entity920 (CM). Intensity data of wavelength @entity13552 are obtained from 25 nm constant offset synchronous fluorescence spectra (SyF), in which are observed distinct peaks (lambda(ex) = 415 nm, lambda(em) = 440 nm; and lambda(ex) = 471 nm, lambda(em) = 496 nm). Wavelength @entity21044 intensity data are obtained from the FA fluorescence excitation and emission maxima (lambda(ex) = 335 nm, lambda(em) = 450 nm; and X(ex) = 471 nm, lambda(em) = 496 nm). Application of MWM shows that the multi-wavelength data sets characterize ligands of different binding strength (log K(x)) and concentration (C(Lx)). Corresponding to pH values of 5, 6, and 7, mean and standard deviation values for wavelength @entity13552 are log K(415/440) = 4.66 (0.12), 5.03 (0.12), and 5.05 (0.08), log K(471/496) = 4.93 (0.06), 5.27 (0.11), and 5.39 (0.09), C(415/440) = 3.1 (1.5), 10.9 (4.5), and 7.9 (3.9) microM, C(471/496) = 14.3 (3.0), 1.7 (0.6), and 1.4 (0.5) microM. And for wavelength @entity21044 , log K(335/450) = 4.50 (0.03), 4.96 (0.27), and 5.22 (0.08), log K(471/496) = 5.02 (0.04), 5.42 (0.32), and 5.71 (0.09), C(335/450) = 8.8 (0.5), 21.9 (7.9), and 18.7 (0.3) microM, C(471/496) = 21.0 (2.5), 7.17 (1.2), and 7.09 (0.3) micrpM. The ability of the 415/440 nm SyF transect to characterize the main excitation and emission maximum of FA at 335/440 nm is evaluated. Relatively low concentration values returned by the model for this transect (415/440 nm) suggest that it is not entirely illustrative of the maximum. The model predictive capability is verified at pH 6 with two fluorescing @entity8863 chelating organic compounds, @entity9109 and @entity3785 . This test confirms that the model is capable of providing good estimates of equilibrium binding parameters from multi-wavelength measurements of a mixed ligand system.
