FIG. 6.
Cis-bixin inhibits the reduction of thioredoxin by thioredoxin reductase. (A) A gel-based assay was devised by using AMS to trap reduced thioredoxin and induce a gel motility shift in this species relative to the migration of oxidized thioredoxin. Gel bands from enzyme reaction product stopped at time points from 0 to 20 min are shown for each of five concentrations of cis-bixin, with densitometry quantitation of gel bands used to construct (B) showing the fraction of reduced thioredoxin produced over time. (C) The fraction of reduced thioredoxin relative to control is shown as a function of cis-bixin concentration at three time points, to allow the determination of IC50 values for the inhibition of reduction of Trx by TrxR1. Data shown are representative of three separate experiments.