Five categories of gating topologies are illustrated at the top of the table. The number of events and percentage for each topology are displayed. Bursts were categorized as described in Materials and methods. Data in this table show that C→O₁→O₂→C is the preferred gating pattern, and a considerable amount of events with more than one O₁→O₂ transition were observed in the MTSES⁻-modified N306C/Cysless. Of note, because of the intrinsic instability of the O₂ state, the analysis method used inevitably overestimates the number of events in the second category and underestimates those in the rest of the categories.