FRAP data processing with three-exponential fitting method

Fluorescence recovery after photobleaching (FRAP) has become a popular technique to investigate the behavior of protein in living cells. There are various mathematical models for the processing of FRAP data. Among them, Compartmental modeling enables researchers to extract information such as the association and dissociation constants, distribution of a protein between mobile and immobilized pools, and the effective diffusion transfer coefficient of the molecule under study. This model is a simple system of linear ordinary differential equations, and its solution used to fit the FRAP data is a simple two exponential function. Therefore, Gustavo Carrero and some other scientists suggest the use of this model. However we find that the length of FRAP data affects the stabilization of data processing. We believe that it is the two-exponential fitting function that causes the instabilization. This paper attempts the study of fitting FRAP data using three exponential sum function and gets better and more stable fitting. As researchers begin to focus on the relative influence of protein domains within individual protein, this approach will allow a quantitative assessment of the relative effect of different molecular interactions on the steady-state distribution of protein in vivo.