Figure 7.

Oxygen-mediated rate-determining reformation of the MPO–sulfide complex mixture. Representative kinetic traces for the reformation of the MPO–sulfide complexes [which we propose is a mixture of MPOFe(III)-hydrosulfido and MPOFe(II)–H₂S complexes] recorded at 430 nm in aerated (blue line) and oxygen-depleted (red line) solutions. Conditions: 2 µM compound I with 100 µM sulfide in 100 mM phosphate buffer, pH 7.4 and 25°C. For the anaerobic measurements, nitrogen was bubbled through the solutions for at least 2 h before use.