Publications [#64945] of Sidney A Simon

Papers Published

1. McIntosh, T.J. and Magid, A.D. and Simon, S.A., Interactions between charged, uncharged, and zwitterionic bilayers containing phosphatidylglycerol, Biophys. J. (USA), vol. 57 no. 6 (1990), pp. 1187 - 97
   (last updated on 2007/04/15)

   Abstract:
   Pressure vs. distance relationships have been obtained for phosphatidylglycerol bilayers, in both charged and uncharged states. Water was removed from the lipid multilayers by the application of osmotic pressures in the range of 0-2.7×10⁹ dyn/cm², and the distance between adjacent bilayers was obtained from Fourier analysis of lamellar X-ray diffraction data. For phosphatidylglycerol bilayers made electrically neutral either by lowering the pH or by adding equimolar concentrations of the positively charged lipid stearylamine, the pressure-distance data could be fit with a single exponential. The measured decay lengths were 1.1 Å at low pH and 1.5 Å with stearylamine, which are similar to decay lengths of the hydration pressure found for gel phases of other neutral bilayers. In addition, the magnitude of this repulsive pressure was proportional to the square of the Volta potential (equivalent to the dipole potential for electrically neutral bilayers) measured in monolayers in equilibrium with bilayers, in agreement with results previously found for the hydration pressure between phosphatidylcholine bilayers

   Keywords:
   bioelectric phenomena;lipid bilayers;X-ray diffraction examination of materials;