Estimated RNA+protein in the cytoplasmic compartment in exponential phase

Range 0.30 to 0.37 Table - link g/ml
Organism Bacteria Escherichia coli
Reference Zimmerman SB, Trach SO. Estimation of macromolecule concentrations and excluded volume effects for the cytoplasm of Escherichia coli. J Mol Biol. 1991 Dec 5 222(3):599-620. p.608 table 3PubMed ID1748995
Method "Rough calculations based upon the composition of E. coli indicate a very high concentration of macromolecules in the cytoplasm. A value of ˜0.62 g of cytoplasmic (RNA + protein) per g dry weight of cells (based on total RNA and total protein values by Neidhardt (1987), allowing 8% of cell dry weight as cell wall protein based upon pp. 246 and 255 of Salton (1964), and allowing 5% of cell dry weight as periplasmic protein based upon the amount of protein released during preparation of spheroplasts) taken with ˜1.5 to 1.8 g of cytoplasmic water per g dry weight of cells (based upon Table 3 of Stock et al. (1977)) yields ˜0.34 to 0.42 g of (RNA + protein) per g of cytoplasmic water. Assuming the specific volume [researchers] find for extract contents (0.67 ml/g), [researchers] expect concentrations of the order of ˜0.3 g of (RNA + protein) per ml of cytoplasm."
Comments "Two protocols are described in Materials and Methods for measuring C[Cytoplasm], i.e. total (protein + RNA) concentrations in the cytoplasm, in terms of sucrose-impermeable cell volume. The results of these two methods are consistent with each other and with the above estimate: C[Cytoplasm] values of ˜0.34 g/ml characterize both exponential and stationary phase cells (Table 3). This value for C[Cytoplasm] is converted with equation (10) to the values for the excluded volume fraction, f, for v=1.0 or 1.3 ml/g in Table 5."
Entered by Uri M
ID 108879