Intracellular buffering capacity of a suspension of spheroplasts

Range 40 to 180 figure - link ng ion H+/pH unit/mg cell dry weight
Organism Bacteria Escherichia coli
Reference Collins SH, Hamilton WA. Magnitude of the protonmotive force in respiring Staphylococcus aureus and Escherichia coli. J Bacteriol. 1976 Jun126(3):1224-31. p.1227 fig.2PubMed ID7546
Method Caption of figure 2:“Buffering powers of extracellular (Bo [black triangle]), intracellular (Bi •), and total space (BT black square), of a suspension of spheroplasts of E. coli. Spheroplasts were prepared as described in Materials and Methods and allowed to equilibrate in 25 ml of sucrose-choline chloride-potassium chloride. Total spheroplast intracellular volume was 50 µl. Bo, BT, and Bi determined as in Fig. 1.[ link ]” Value extracted visually from fig.2
Comments "The purpose of the experiments reported in this communication was to obtain a measure of the magnitude of the protonmotive force that is developed across the cytoplasmic membrane of respiring Staphylococcus aureus and Escherichia coli." “Figure 2 shows similar curves [typical experimental curves of the buffering power (dH+/ dpH)] for the determination of Bo, BT, and Bi for suspensions of spheroplasts of E. coli. Since dry weights of the spheroplast suspension could not be simply determined, cell volume was estimated in each experiment as a fraction of the total suspension volume, and the results in this case were expressed as nanogram-ions of H+ per pH unit per milliliter of spheroplast suspension. The intracellular spheroplast volume in this particular case was 50µl in the total volume of 25 ml.”
Entered by Uri M
ID 107127