Altering the activity of syringomycin e via the membrane dipole potential

The membrane dipole potential is responsible for the modulation of numerous biological processes. It was previously shown (Ostroumova, O. S.; Kaulin, Y. A.; Gurnev, P. A.; Schagina, L. V. Langmuir 2007, 23, 6889-6892) that variations in the dipole potential lead to changes in the channel properties of the antifungal lipodepsipeptide syringomycin E (SRE). Here, data are presented demonstrating the effect of the membrane dipole potential on the channel-forming activity of SRE. A rise in the dipole potential is accompanied by both an increase in the minimum SIZE concentration required for the detection of single channels at fixed voltage and a decrease in the steady-state number of open SIZE channels at a given SIZE concentration and voltage. These alterations are determined by several factors: gating charge, connected with translocations of lipid and SIZE dipoles during channel formation, the bilayer-water solution partitioning of SIZE, and the chemical work related to conformational changes during channel formation.