TABLE 1.

Apparent midpoint redox potentials of the redox cofactors measured at different pH values Data were from optical titrations. The errors were determined from the 95% confidence bounds of the fitting results.

Redox cofactor	Em,6	Em,7	Em,8
	mV	mV	mV
Heme b	428 ± 2	418 ± 3	410 ± 3
Heme c	356 ± 9	351 ± 8	341 ± 4
Heme c	330 ± 9	320 ± 7	293 ± 4
Heme c	258 ± 5	234 ± 5	210 ± 5
Heme b3	–38 ± 2	–59 ± 2	–77 ± 2
CuBa	∼350	∼330	∼290

^aThe values are approximations from the optical data