TABLE 3.

Specific activity and heme contents of membranes obtained from the anaerobically grown cells^a

Strain or plasmid	Succinate-acceptor reductase activity (2 electron equivalents/min/mg of protein) (10−6)			Heme b556b (nmol/mg)	Turnover numberc (S−1)	Amplification leveld	Doubling time (h)
	PES	K3Fe(CN)6	Q2
frdABCD plasmid
MC4100 (wild type)	0.6	0.6	0.3		25	1	1.6
pH3-177	6.1	6.6	3.3		27	11	1.6
pH3	7.6	9.4	4.6		28	15	1.8
sdhCDAB plasmid
pFGS-177	14	—f	12.8	2	102	11	3.3
pFGS	18.8	—	17.5	2.7	105	15	3.0
pFAS	24	—	22	3.6	102	19	7.6
pSDH15	2.7	—	2.3	0.4	96	2	>8
Aerobically grown cellse (pSDH15)	10.5	—	9.4	1.5	100	NDg	ND

^aAll cells were DW35 except the MC4100 wild type. 

^bDetermined as level reduced with dithionite minus level reduced with ascorbate-TMPD. 

^cBased on succinate-Q₂ reductase reaction. 

^dCompared to wild-type expression of QFR in MC4100. 

^eCultures were grown aerobically on the same medium as anaerobically grown cultures except that 25 mM succinate replaced fumarate. 

^fSQR does not show succinate-ferricyanide reductase activity. 

^gND, not determined.