Fig. 4.

Oxygen is reduced by Ero1p activity to form hydrogen peroxide. (A) The reaction was initiated at time 0 by injecting the shorter construct of Ero1p to a final concentration of 1 μM into a solution containing 50 μM Trx_red, and oxygen consumption was monitored. Approximately half of the oxygen originally consumed during Trx_red oxidation was restored with the addition of catalase (arrow), indicating that oxygen has been reduced to H₂O₂ in the initial reaction. Similar results were obtained for the longer construct. (B) The reaction was initiated at time 0 by injecting the shorter form of Ero1p to a final concentration of 1 μM into a rapidly stirred solution containing 100 μM Trx_red. Samples were withdrawn and mixed with the PeroXOquant detection reagent. Absorbance values were converted to H₂O₂ concentration according to a standard H₂O₂ calibration curve.