Fig 1.

HOCl generation by VPO1. (A) Comparison of the peroxidase activities of MPO, bLPO, and rVPO1 determined using TMB as a substrate as described in Materials and Methods. A 110-μl reaction contained 100 μl of TMB, 10 nM/heme MPO, 50 nM/heme bLPO, or 50 nM/heme rVPO1. The reaction (n = 9) was carried out at 37°C for 30 min, and the absorbance at 650 nm was recorded. (B) Detection of Cl-tau generation by the A₂₅₂. Cl-tau generation was carried out in a 100-μl reaction that contained 50 mM potassium phosphate buffer (pH 5.5), 5 mM taurine, 0.8 mM H₂O₂, 100 mM Cl⁻, and either 100 nM/heme MPO, 100 nM/heme bLPO, or 1 μM/heme rVPO1. Reactions without Cl⁻ were also performed. The absorbance at 252 nm was recorded every 30 s for 15 min.