5] Changes of surface and membrane potentials in biomembranes

Abstract

Publisher Summary This chapter describes the methods used to measure the membrane potential and the surface potential in biological membranes. According to the chemiosmotic theory developed by Mitchell, the difference in the electrochemical potential of proton across the membrane is an intermediate for adenosine triphosphate (ATP) synthesis and is the motive force for active transport. The difference expressed in the unit of volt is called “protonmotive force.” It is composed of two terms, the membrane potential and pH difference. The biological membrane is usually negatively charged at neutral pH. In the electrolyte solution, which is contiguous to the charged membrane, an electric double layer forms where an electric field extends from the membrane surface to the bulk solution. The surface potential is defined as the “electrical potential” at the membrane surface with reference to the potential in the bulk aqueous phase. It is reported that the changes in the surface potential are associated with many functions of biomembranes.