Ligand-gated ion channel and path integral approach to biological complex systems

Abstract

In this dissertation we study the ligand binding in biological complex systems. The study is divided into two parts. The first part is devoted to the study of the Ligand gated ion channel current in the nonstationary lyotropic system. The model proposed by Liu and Dilger (1993) was applied to this system and compared with the nonstationary ion channel model developed by Matsson (1996), Grzegorczyk, Jacobsson, Jardemark and Matsson (1998), and Matsson, Sa-yakanit, and Boribarn (2003). The main quantities of interest are the open channel probability and the mean current. The derived total currents fit recorded data better than other stationary type models. The second part is devoted to the study of the ligand binding in heme following from Sa-yakanit and Boribarn (2001). The problem of survival paths for reaction dynamics in fluctuating environment using the functional integral has been considered by Wang and Wolynes (1993, 1994). This approach assumed at the beginning that the fluctuation relax exponentially according to the stretched exponential law. We derive the rate reaction and the correlation function from the microscopic model given by Caldeira and Legget (1983). Using the path integral technique developed by Sa-yakanit for handling the disordered system, we obtain the effective rate reaction and the correlation functions.