Authors: D.P. Chen, J. Tang and R.S. Eisenberg
Affilation: Rush Medical College, United States
Pages: 64 - 67
Keywords: porin, Poisson-Nernst-Planck, electrodiffusion, semiconductor equation
Single channel current-voltage (IV) relations were measured from proteins that form channels across the outer membranes of Gram-negative bacteria-porins and their mutants in solutions of KCl. The wild-type porins and some of their specific mutants have known x-rays structures, which lays the foundation for this theoretical work. The ionic strength of KCl ranges from 100mM to 3M. Using the already published electrodiffusion permeation theory —, the measured IV relations were analyzed by the Poisson-Nernst-Planck (PNP) formulation. The parameters of the permeation property in the theory are obtained by the least-squares fit to the experimental data and compared to the known structure changes in the wild-type porins and their mutants. The comparison shows that the PNP theory can successfully recover the charge difference between the wild-type and mutants; hence, the theory begins to establish the structure-function relation biological charge transport systems and other macro-molecules.