Z Bajzer, AC Myers, SS Sedarous, and FG Prendergast. Pade-Laplace method for analysis of fluorescence intensity decay. Biophys. J. 56: 79-93.
Z Bajzer, AC Myers, SS Sedarous and FG Prendergast
Department of Biochemistry and Molecular Biology, Mayo Foundation, Rochester, Minnesota 55905.
This novel approach to the analysis of multiexponential functions is based on the combined use of the Laplace transform and Pade approximants (Yeramian, E., and P. Claverie. 1987. Nature (Lond.). 326:169-174). It is similar in principle to the well-known Isenberg method of moments (Isenberg, I. 1983. Biophys. J. 43:141-148) traditionally applied to the analysis of fluorescence decay. The advantage of the Pade-Laplace method lies in its ability to detect the number of components in a multiexponential function as well as their parameters. In this paper we modified the original method so that it can be applied to the analysis of multifrequency phase/modulation measurements of fluorescence decay. The method was tested first on simulated data. It afforded recovery up to four distinct lifetime components (and their fractional contributions). In the case of simulated data corresponding to continuous lifetime distributions (nonexponential decay), the results of the analysis by the Pade-Laplace method indicated the absence of discrete exponential components. The method was also applied to real phase/modulation data gathered on known fluorophores and their mixtures and on tryptophan fluorescence in phospholipase A2. The lifetime and fraction recoveries were consistent with those obtained from standard methods involving nonlinear least- square fitting.