The Journal of Membrane Biology

A chemically synthesized peptide consisting of the C-terminus of the M protein of the Dengue virus type 1 strain Singapore S275/90 (DVM-C) produced ion channel activity in artificial lipid bilayers. The channels had a variable conductance and were more permeable to sodium and potassium ions than to chloride ions and more permeable to chloride ions than to calcium ions. Hexamethylene amiloride (100 μM) and amantadine (10 μM), blocked channels formed by DVM-C. Ion channels may play an important role in the life cycle of many viruses and drugs that block these channels may prove to be useful antiviral agents.

The membrane permeability coefficients for the homologous monocarboxylic acids, formic through hexanoic, as well as benzoic and salicylic, were determined for egg phosphatidylcholine-decane planar bilayer membranes. The permeabilities of formic, acetic and propionic acid were also determined for “solvent-free” phosphatidylethanolamine bilayers. Permeability coefficients were calculated from tracer fluxes measured under otherwise symmetrical conditions, and precautions were taken to ensure that the values were not underestimated due to unstirred layer effects. The relation between the nonionic (HA) permeability (P m ) and the hexadecane/water partition coefficient (K p ) was: log m =0.90 log Kp+0.87 (correlation coefficient=0.996). Formic acid was excluded from the analysis because its permeability was sixfold higher than predicted by the other acids. The permeabilities for “solvent-free” membranes were similar to those for decanecontaining membranes. The exceptionally high permeability of formic acid and the high correlation of the other permeabilities to the hexadecane/water partition coefficient is a pattern that conforms with other nonelectrolyte permeabilities through bilayers. Similarly, the mean incremental free energy change per methylene group (σΔG-CH2-) was −764 cal mol−1, similar to other homologous solutes in other membrane systems. However, much less negative σΔG values (−120, to −400 cal mol−1) were previously reported for fatty acids permeating bilayers and biological membranes. These values are due primarily to unstirred layer effects, metabolism and binding to membranes and other cell components.