FIG. 3.

Transformation of PNP by an E. coli lysate containing NpdA2. The rates of substrate disappearance (PNP [▪]) and product appearance (hydroxyquinol [•] and hydroquinone [▴]) are averages from at least three assays, carried out using independent preparations of E. coli BL21(DE3)(pLysS, pLP261), as described in Materials and Methods. Samples were withdrawn at the indicated time points and treated immediately with glacial acetic acid (1%) and sodium dithionite (1 mM) to stop the reaction and reduce quinones to quinols. Substrates and products were quantified by HPLC.