Figure 4.
Activity of PNPase under various treatment conditions. E. coli cultures were grown in YT medium. At OD550nm = 0.5, the cultures of the wild-type strain were treated with various chemicals at concentrations shown in the legend. Cells were collected at the indicated time points. PNPase polymerization activity was measured by ADP incorporation into RNA as described in Materials and Methods using 18 μg of protein from cell extracts in a 50 μL reaction. The averages of two measurements and standard errors are shown.