FIG. 3.

Kinetics of PGH activity from E. coli. Shown is the effect of the PABA-GLU concentration on the initial velocity of PGH activity of purified enzyme isolated from E. coli MG1655 transformed with pLenABHis. A spectrophotometric assay was utilized, as described in Materials and Methods. The reaction mixtures (1.6 ml) consisted of buffer and various concentrations of PABA-GLU (67, 100, 175, 400, and 800 μM). The reaction was initiated by the addition of Ni-NTA agarose-purified enzyme (3.1 μg), and the mixture was incubated at 37°C. The concentration of PABA-GLU is plotted versus the initial velocity. The data were analyzed using GraphPad Prism 5. The error bars indicate standard deviations.