Thermodynamic constants for nonelectrolyte partition between dimyristoyl lecithin and water

Abstract

Summary. Partition coefficients (K's) between dimyristoyl lecithin liposomes and water were measured as a function of temperature for 16 nonelectrolytes. From K and its temperature dependence, the partial molar free energy (,JF), enthalpy (,JH) and entropy (LtS) of partition for each solute were extracted. By subtraction of dE', AH and AS of hydration of each solute (where known), AF, zlH and AS of solution in lecithin could be calculated for some solutes. Among different solutes AS of solution increases approximately linearly with AH of solution, as also found in bulk solvents (the so-called Barclay-Butler relations). The Barclay-Butler slope dztS/dzlH is approximately twice as steep for lecithin as for bulk nonpolar solvents. This effect is attributed in part to greater immobilization of solutes in bilayers than in bulk solvents.The previous papers in this series described methods for measuring nonelectrolyte partition coefficients between liposomes and water, and for estimating the amount of nonsolvent water in liposomes (Katz & Diamond, 1974a, b, referred to as papers I and II, respectively). The present paper reports experimental measurements of partition coefficients between dimyristoyl lecithin liposomes and water, corrected for the effects of trapped water and nonsolvent water in the liposomes. It then extracts the following thermodynamic parameters from these measurements: partial molar free energies, enthalpies, and entropies of partition; partial molar free energies, enthalpies, and entropies of solution in lecithin from the gas phase; and the Barclay-Butler constants for solution in lecithin.

Alcohols lower the threshold temperature for the maximal activation of a heat shock expression vector in the yeast Saccharomyces cerevisiae

“…The lipid : water partition coefficient of alcohols increaces with increasing carbon-chain length (Katz & Diamond, 1974). That a proportionally lower concentration of alcohol elicited the same shift in the maximum HSR threshold as the carbon-chain length increased, supports the hypothesis that the membrane plays a role in modulating the cell's response to an increase in temperature.…”

Effects of alcohols on the respiration and fermentation of aerated suspensions of baker's yeast

“…tory than ethanol towards anaerobic C 0 2 production whereas higher alkanols were more inhibitory. When the logarithm of the alkanol concentration giving 50% inhibition of anaerobic C 0 2 output was plotted against the logarithm of its partition coefficient between dimyristoyl lecithin and water (Katz & Diamond, 1974) a good correlation was obtained (Fig. 2).…”

“…1 in the presence of different concentrations of various alkanols, and the alkanol concentration that gave 50% inhibition of anaerobic C 0 2 production was calculated. The logarithm of this concentration was plotted against the logarithm of the partition coefficient of the alkanol in the dimyristoyl lecithinlwater system (Katz & Diamond, 1974). tory than ethanol towards anaerobic C 0 2 production whereas higher alkanols were more inhibitory.…”

Membrane-Water Partitioning of Polychlorinated Biphenyls in Small Unilamellar Vesicles of Four Saturated Phosphatidylcholines

“…Gobas et al observed a significant stronger influence of the molar volume of the solute on the partition coefficient between water and membrane vesicles than on the partition coefficients between water and the bulksolvents hexane and 1-octanol indeed (1 7). Also Katz and Diamond concluded from their thermodynamic study on the transfer of 16 nonelectrolytes from water into membrane liposomes that the extra decrease in entropy during the solution of the solute in the liposomes compared to the solution in a bulk solvent is due to the stronger immobilization of the solute molecules in the more structured membrane phase (18). Omann and Lackowicz observed a reverse relation between the lipid package density of the membrane and the partitioning of chlorinated hydrocarbons in membrane vesicles (1 0).…”