SURFACE POTENTIAL OF BLM AND KINETICS OF PORIN INCORPORATION

Porins belong to a class of integral membrane proteins which are able to form channels characterized by voltage dependence. The molecular mechanism by which the protein is influenced by a change in voltage is unknown, but the study in the presence of substances that influence the surface potential can be useful to shed light on the problem. As this class of proteins sense the difference in transmembrane potential, in order to gain further insight into the structure of proteins and their kinetics of incorporation, the best tool at hand is to insert these proteins into the BLM with different surface charge in the presence of ions that affect the surface potential. In this report we studied the kinetics of incorporation of mitochondrial porin in the presence of divalent alkaline earth calcium and barium, that are known to influence the surface potential of negatively charged bilayer membranes. The effect that these ions exert on the incorporation of the porin in negatively charged BLM is discussed.