Fig 8. Kinetic characterization of Arg300Ser PDS.

Dependence of Arg300Ser PDS reaction rates on phytoene (A) and DPQ (B). (C) Inhibition kinetics of Arg300Ser PDS in a matrix of varying DPQ and NFZ concentration. Data points represent the mean of duplicates ± SEM. In A and B: ■, ζ-carotene; ○, phytofluene; Δ, ζ-carotene:phytofluene ratio. Data in A (R² = 0.58) and B (R² = 0.95) were fitted with the Michaelis-Menten equation and the equation for competitive inhibition was applied in C (R² = 0.92) using the GraphPad Prism 5 software (for equations, see Methods). The product:intermediate ratios in A and B (dotted lines; plotted to the right Y-axis) was fitted using a spline. Assays were carried out under standard conditions and incubated for 15 min (see Methods).