Fig. 5.

Products formed from PCP by PcpB in the presence and absence of PcpD. (A) The rates of reaction of TCBQ with β−ME and PcpD under the experimental conditions. (B) The amount of PCP consumed is shown in light gray bars, the amount of TCHQ formed is shown in dark gray bars, and the amount of THTH formed is shown in black bars. Reactions contained 2.8 µM PcpB, 100 µM PCP, 50 µM NADPH, 50 µM NADH, 6 mM β-ME in the presence or absence of 10 µM PcpD. The discrepancies between the amounts of PCP used and the amounts of TCHQ or THTH formed are due to (i) the rapid reaction of TCBQ with thiols, especially in the absence of PcpD; and (ii) the difficulty in monitoring relatively small amounts of PCP disappearance by HPLC, which leads to relatively large errors in quantitation.