Table 2.

Lifetimes of proton uptake measured at pH 7.5 on formation of Q_A⁻ or Q_B⁻

Strains	H+/QA−*		H+/QB−, first flash†		H+/QB, second flash†
	Fast	Slow	Fast	Slow	Fast	Slow
Wild type‡	≈ms	—	≈ms	—	≈ms	—
L212Q	≈ms	—	≈ms	—	≈ms	1.5 s
L212A	≈ms	—	≈ms	—	≈ms	—
L212A-L213A	≈ms	0.99 s	<25 ms	0.78 s	<25 ms	0.80 s
AA+M231L	≈ms	—	<25 ms	—	<25 ms	—
AA+M43D	≈ms	—	<25 ms	—	<25 ms	0.12 s
AA+M5D	≈ms	0.40	<25 ms	0.31 s	<25 ms	0.35 s
AA+M247Y	≈ms	0.56	<25 ms	0.67 s	<25 ms	0.60 s

The standard deviations for the slow components are 10% of the values. “≈ms” holds for lifetime values in the millisecond time range (or very few milliseconds; data not shown). “<25 ms” is a higher limit for slightly longer components seen in a different time window (not shown here). These differences are not resolvable on the time scale of the present experiments. 

^*Terbutryn added. 

^† Excess quinone present. 

^‡ See Table 1 for wild-type residues and mutant designations.