In vitro Sumoylation assay revealed that Prdx6 was modified by Sumo1. The in vitro Sumoylation assay was performed according to the manufacturer’s protocol. Briefly, a combination of E1 enzyme, E2 (Ubc9) enzyme, Sumo1 wild-type (WT) protein and/or Sumo1 mutant protein and different concentrations of recombinant Prdx6 protein (TAT-HA-Prdx6) were mixed with 20μl reaction mixture containing Sumoylation buffer. Following incubation at 30°C for 3h, reaction product was incubated at 90°C with 2X SDS-gel loading buffer and was immunoblotted using anti-Sumo1 and anti-Prdx6 polyclonal antibodies. Concentration-dependent Sumoylation of recombinant wild-type Prdx6 protein was seen, as shown in figure, lanes 1 and 2 (* denotes the Sumoylation band). Mutant Sumo1 failed to conjugate to Prdx6, suggesting Prdx6 was Sumoylated in vitro.