Purification and characterization of Arabidopsis OPRs. A, SDS-PAGE analysis of affinity-purified Arabidopsis OPR1, OPR2, and OPR3 from E. coli. Lane M contains protein markers. B to E, Time course of TNT disappearance and product formation from purified in vitro assays analyzed by HPLC. B and C, OPR1. D, OPR2. E, OPR3. 2H-TNT, Hydride Meisenheimer complexes and elution times. Results are means of three replicates ± sd.