High magnesium content of Escherichia coli B.

We have found that the intracellular concentration of magnesium in exponentially growing Escherichia coli B is much higher than has been previously assumed; it is about 100 mM. Results of equilibrium dialysis suggest that nearly all of this Mg is bound, probably most of it to nucleic acids. These findings could have important consequences for the study of protein-DNA interactions and the in vitro simulation of protein biosynthesis.