Mpo from human leukocytes

KYNA was purchased from ChemCruz (Dallas, TX). NaBr (>99.99%), NaCl (>99.99%), KH₂PO₄, K₂HPO₄, MPO from human leukocytes, and EPO human recombinant protein were purchased from Sigma-Aldrich (St. Louis, MO). Other chemicals were obtained from Nacalai Tesque (Kyoto, Japan) or TCI (Tokyo). Bromide-free hypobromous acid (HOBr) was prepared by the addition of silver nitrate and subsequent distillation, as previously reported.^{(21 (link))} The concentration of HOBr was determined spectrophotometrically at 331 nm in 10 mM NaOH using a molar extinction coefficient of 315 M⁻¹ cm⁻¹.^{(22 )} Chloride-free sodium hypochlorite (NaOCl) was prepared by the method previously reported.^{(23 (link))} The concentration of NaOCl was determined spectrophotometrically at 290 nm using a molar extinction coefficient of 350 M⁻¹ cm⁻¹.^{(24 )}