Poisson-Boltzmann theory for membranes with mobile charged lipids and the pH-dependent interaction of a DNA molecule with a membrane.
We consider a planar stiff model membrane consisting of mobile surface groups whose state of charge depends on the pH and the ionic composition of the adjacent electrolyte solution. To calculate the mean-field interaction potential between a charged object and such a model membrane, one needs to solve a Poisson-Boltzmann boundary value problem. We here derive and discuss the boundary condition at the membrane surface, a condition that is generally appropriate for biological membranes where two charge-regulating mechanisms are present at the same time: the pH-dependent chemical charge regulation and a regulation through the in-plane mobility of the surface groups. As an application of this general formalism, we consider the specific example of a single DNA molecule, approximated by a cylinder with smeared-out surface charges, interacting with such a model membrane. We study the effect that the two competing charge-regulating mechanisms have on the DNA/membrane interaction and the distribution of surface ions in the plane of the membrane. We find that, at short DNA-membrane distances, membrane fluidity can have a considerable impact on the DNA adsorption behavior and can lead to such counterintuitive phenomena as the adsorption of a negatively charged DNA onto a (on average) negatively charged membrane.
Fleck
Christian
C
Fakultät für Physik, Universität Konstanz, 78457 Konstanz, Germany. Christian.Fleck@uni-konstanz.de
Netz
Roland R
RR
von Grünberg
Hans Hennig
HH
D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D004573:Electrolytes / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008563:Membrane Lipids / Q000502:physiology*; D008566:Membranes / Q000502:physiology*; D008954:Models, Biological; D016012:Poisson Distribution
D004573:Electrolytes; D008563:Membrane Lipids; D004247:DNA