The nature and magnitude of the surface dipole potential chi at a membrane/water interface still remain open to discussion. By combining measurements of differential capacity C and charge density sigma at the interface between self-assembled monolayers of phosphatidylserine and phosphatidic acid supported by mercury and aqueous electrolytes of different concentration and pH, a sigmoidal dependence of chi upon sigma is revealed, with the inflection at sigma = 0. This behavior is strongly reminiscent of the surface dipole potential due to reorientation of adsorbed water molecules at electrified interfaces. The small increase in C with a decrease in the frequency of the AC signal below similar to 80 Hz, as observed with phospholipid monolayers with partially protonated polar groups, is explained either by a sluggish collective reorientation of some polar groups of the lipid or by a sluggish movement of protons across the polar head region.
Surface dipole potential at the interface between water and self-assembled monolayers of phosphatidylserine and phosphatidic acid / M.R. MONCELLI; L. BECUCCI; F. TADINI BUONINSEGNI; R. GUIDELLI. - In: BIOPHYSICAL JOURNAL. - ISSN 0006-3495. - STAMPA. - 74:(1998), pp. 2388-2397.
Surface dipole potential at the interface between water and self-assembled monolayers of phosphatidylserine and phosphatidic acid
MONCELLI, MARIA ROSA;BECUCCI, LUCIA;TADINI BUONINSEGNI, FRANCESCO;GUIDELLI, ROLANDO
1998
Abstract
The nature and magnitude of the surface dipole potential chi at a membrane/water interface still remain open to discussion. By combining measurements of differential capacity C and charge density sigma at the interface between self-assembled monolayers of phosphatidylserine and phosphatidic acid supported by mercury and aqueous electrolytes of different concentration and pH, a sigmoidal dependence of chi upon sigma is revealed, with the inflection at sigma = 0. This behavior is strongly reminiscent of the surface dipole potential due to reorientation of adsorbed water molecules at electrified interfaces. The small increase in C with a decrease in the frequency of the AC signal below similar to 80 Hz, as observed with phospholipid monolayers with partially protonated polar groups, is explained either by a sluggish collective reorientation of some polar groups of the lipid or by a sluggish movement of protons across the polar head region.I documenti in FLORE sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.