Electromigration of polyion homopolymers across biomembranes: a biophysical model

The analysis of polyion transmembrane translocation was performed using mem brane electrical equivalent circuit. The dependence of polyion flux across membranes on time, membrane electrical conductance, membrane electrical cap acitance, degree of polymerization, water solution conductance and applied transmembrane potential is discussed. The changes in polyion flux were up t o 88% after 1 ms. Both the increase of polyion chain length and the decreas e of membrane conductance resulted in the diminution of this effect. Invers ion of flux direction was observed as a result of external potential change s. Reversal curves, representing the values of considered parameters for ze ro-flux were also shown. The replacement of a polyanion by a polycation of the same chain length resulted in the same shape of the surface plot but wi th opposite orientation. The analysis describes the effect of transmembrane potential on the translocation rate of polyanionic polysialic acid and pol ynucleotides, and polycationic peptides across membranes. (C) 2000 Elsevier Science B.V. All rights reserved.