TABLE 1.

Various properties of R. capsulatus strains harboring a cytochrome b₆c₁ complex or a cytochrome bc₁ complex

Strain	Growth (min)a	Inhibitor responseb	Cytochrome b (μM)c	DBH2-cytochrome c reductase (%)d	Em7 (mV)		λmax (nm)		I50 (nM)e	Qo → bHf		Qo → cf
					bH	bL	bH	bL		Rate (s−1)	Eh (mV)	Rate (s−1)	Eh (mV)
MT-RBC1/pMTS1 (cytochrome bc1 complex)	150	Myxs	1.97	100	49	−125	560	558, 565	15	529	106	240	100
		Stgs								118	208
MT-RBC1/pSM1 (cytochrome b6c1 complex)	210	MyxHS	0.44	7	56	−110	560	560	7.6	NDg	ND
		StgHS								ND
MT-RBC1/pSM1-92 (cytochrome b6c1 complex)	180	Myxs	0.76	42	46	−132	560	560	15	335	115	174	106
		Stgs								112	200

^aDoubling time under PS growth conditions in MPYE medium. 

^bMyx and Stg correspond to myxothiazol and stigmatellin, respectively. S and HS indicate sensitivity (inability to grow in the presence of 10⁻⁶ M) and hypersensitivity (inability to grow in the presence of 10⁻⁷ M) to these inhibitors, respectively. 

^cTotal amount of cytochrome b estimated from reduced minus oxidized optical difference spectra with an ɛ_560–570 of 28 m⁻¹ cm⁻¹. 

^dCytochrome c reductase activity was determined as nanomoles of horse heart cytochrome c reduced per minute per milligram of total membrane proteins with DBH₂ as an electron donor and was normalized for the amount of g_y signal of the Fe-S protein as measured by EPR spectroscopy. In this instance, 100% corresponds to 7,099 nmol of cytochrome c reduced per min per mg of protein, normalized to the amplitude of the g_y signal as shown in Fig. 5. 

^eI₅₀ refers to the concentration of antimycin A required to inhibit by 50% the cytochrome c reductase activity detected. 

^fQ_o → b_H and Q_o → c electron transfer rates were obtained by fitting the cytochrome b reduction and cytochrome c rereduction traces (not shown) to a single exponential equation, as described previously (31). E_h is the ambient potential at which the measurements were done, and c indicates the total amount of the cytochromes (c₁ + c₂ + c_y). 

^gND, not done.