Figure 8. Optimal conditions for PPO activity.

The activity of purified recombinant PPOs was monitored by spectrophotometry at 405-methylcatechol. (A) The influence of pH on PPO activity was determined using 100 mM acetate-phosphate buffer with the pH adjusted by adding NaOH. Activities were measured in the presence of 0.75 mM SDS (PPOs 2, 6 and 7) or 1.0 mM SDS (PPO-1). (B) Influence of SDS concentration on PPO activity. All measurements were taken at the optimal pH for each PPO (pH 5.0 for PPO 6 and 7, pH 5.5 for PPO-1, and pH 6.0 for PPO-2). All values are means ± standard deviation from one representative experiment measured in triplicate.