Using a chimeric respiratory chain and EPR spectroscopy to determine the origin of semiquinone species previously assigned to mitochondrial complex I

Table 1 Representative kinetic measurements on SMPs and AOX-SMPs. AOX-SMPs were preincubated with antimycin A. For assay details, see “Methods”

	NADH:O₂ (μmol min^− 1 mg^− 1)			Succinate:NAD⁺ (RET) (μmol min^− 1 mg^− 1)		Inhibition of NADH oxidation (%)		Δp (mV)
	−Gram	+Gram	RCR	−Gram	+Gram	Piericidin A	Quinol oxidation^a
SMPs	0.301 ± 0.008	0.626 ± 0.011	2.08 ± 0.05	0.092 ± 0.004	0.009 ± 0.001	98.7 ± 0.01	95.8 ± 0.03	161.4 ± 0.2
AOX-SMPs	0.288 ± 0.026	0.360 ± 0.028	1.25 ± 0.03	0.065 ± 0.004	0.007 ± 0.005	99.2 ± 0.01	97.1 ± 0.01	157.9 ± 1.6

^aQuinol oxidation was inhibited by antimycin A in SMPs, and antimycin A and ascofuranone in AOX-SMPs

ISSN: 1741-7007