Table 1.

The calculated redox midpoint potentials (E_m,₇ at pH 7; in mV) of the redox-active cofactors for the different steps in the reaction cycle during the O to E transition in bovine CcO

Calculation/Experiment	Transfer step	Redox–active centers
		CuA		Fea		Fea3		CuB
phase 1:	[ET]	258a	⥂	270		150		0
				140b		17[b]
phase 2:	[PTpump/ET]	238		340	⥂	350		240
phase 3:	[PTchem/ET]	267		380		355	→	490
phase 4:	[pumping]	267		278		120		240
Exp.1:c	pH 7.0	212–258		254–281		n.a.g		227–272
	pH 7.0	224		267		n.a.		230
Exp.2:d	pH 7.0	230–265		267–359		300–360		>400
Exp.3:e	pH 7.0	270		342		330		n.a.
Exp.4:f	pH 6.5	250		391 (238)		383 (405)		412
	pH 8.0	250		359 (222)		350 (372)		366

^aThe E_m of the Cu_A center is adopted from ref. [89], see text for details.

^bThe calculated E_ms of heme a and heme a₃ in phase 1, if residue E242 is in its deprotonated state.

^cSteady-state redox potential ranges of the metal centers in bovine CcO, taken from ref. [89], see also refs therein.

^dThe range of E_m values obtained from the equilibrium experiments performed in the anaerobic conditions or in the presence of an inhibitor (CO, CN⁻, NO, etc.) in the BNC of bovine CcO, summarized from refs. [90, 93, 95, 97].

^eThe E_ms of the metal centers in bovine CcO obtained by fitting the experimental data to theoretical model. [55]

^fExperimental E_ms of the redox centers, at pH 6.5 and 8.0, in CcO from P. denitrificans. For heme a and heme a₃ are listed their high-asymptotic redox potentials. The numbers in brackets refer to the low-potential and high-potential heme transitions, see ref. [98] for details.

^gData are not available.