Ion distributions and their relationship to periplasmic osmotic strength in E. coli and Salmonella typhimurium

Range Table - link
Organism Various
Reference Stock JB, Rauch B, Roseman S. Periplasmic space in Salmonella typhimurium and Escherichia coli. J Biol Chem. 1977 Nov 10 252(21):7850-61 p.7859 table VIPubMed ID334768
Method P.7851 left column 3rd paragraph: "The cytoplasmic, periplasmic, and total cell volumes were all derived from the distributions of solutes in cell suspensions, The rationale is illustrated in Fig. 1. Inulin, because it is large, cannot penetrate the outer membrane and is located only in the extracellular fluid. Sucrose, without the aid of a permease, cannot cross the plasma membrane and is located only in the periplasm and extracellular fluid. Water moves freely throughout the cell, it is located in the cytoplasm, periplasm, and extracellular fluid."
Comments P.7859 left column 3rd paragraph: "As shown in Table VI, experiments with radiolabeled Na+ and Cl- showed that each of these ions distributed unequally across the outer membrane. From the measured volumes, the potential across the outer membrane (E[om]) was estimated, and essentially the same values were obtained by using either the Na+ or Cl- distribution. The value for E[om] was between 17 and 31 mV for cells in Medium 63. Membrane potentials generated by Donnan equilibria are sensitive to the ionic strength of the medium. This was true for the potential across the outer membrane. Based on Na+ distribution measurements, E[om] was only about 5 mV for cells in 200 mM potassium phosphate, pH 7.3, and increased to approximately 80 mV for cells in 5.0 mM potassium phosphate (Medium 63 contains 50 mM potassium phosphate). Since any ion in the medium should distribute itself according to this potential, the ionic composition of the periplasm of cells in a solution such as Medium 63 could be estimated, and this is presented in Table VI."
Entered by Uri M
ID 104057