Figure 3.

PFT-α inhibits active and recombinant firefly luciferase. (A) Exogenously added PFT-α inhibits cell extracts containing luciferase activity in vitro. HFF cells were transiently transfected with 1.5 μg of PG13 reporter plasmid. Cellular extracts were obtained, serial dilutions of PFT-α were added as indicated, and luciferase activity was measured. Results are expressed as the mean plus standard deviation of a minimum of 3 independent experiments. (B) PFT-α inhibits the activity of purified recombinant luciferase protein. Recombinant firefly luciferase was incubated with luciferase substrate in the presence or absence of 20 μM PFT-α and luciferase activity was measured. Results are expressed as light units, and represent mean plus standard deviation of a minimum of 3 independent experiments. Error bars are beneath the resolution of the graph and although calculated, cannot be seen. (C) PFT-α inhibits the activity of purified recombinant luciferase protein independently of substrate concentration. Recombinant firefly luciferase was incubated with increasing concentrations of luciferase substrate in the presence or absence of 20 μM PFT-α and luciferase activity was measured. Results are expressed as light units, and represent mean plus standard deviation of a minimum of 3 independent experiments. Luciferase substrate concentration is not provided by the manufacturer (Promega) and therefore is expressed as μl of substrate used.