Scheme 23.

Catalytic Mechanism of O₂-Reduction by HCOs^a

^aReduction potential values obtained from refs 875–878 shown as a range of values obtained using various methods or conditions. Heme-a₃ peripheral R group = 15-C farnesyl group, see Figure 89C. See text, both here and in section 6, for clarification or further alternative descriptions of the intermediates depicted here, or for unobserved putative intermediates.