ABSTRACT
The surface charge and surface potential of biological membranes can influence their permeability, transport processes, and enzymic function. A difference in the electric potential is formed at the boundary between two phases due to the transfer of ions and/or electrons from one phase to another. Ions of the charge which is opposite to that of the surface are concentrated in the vicinity of the surface due to electrostatic attraction, whereas ions of the same charge are repulsed. The Gouy-Chapman theory assumes that ions are point charges and that their interaction with the solid phase is electric nature. Biological membranes can be regarded as a solid phase in spite of a certain fluidity of their lipid components and motion of integral proteins. Soluble enzymes immobilized on solid supports can be regarded as models for enzymes bound to biological membranes. The surface potential can affect enzyme kinetics not only by altering the local concentration of substrates, but also that of charged activators.
