TABLE 2.

FRET efficiencies and calculated distances between probes on 219–219 and 642–642 cysteine pairs of mutant CtH⁺-PPases

The value of FRET efficiencies (E*, %) are the mean (± S.D.) from the indicated number of single molecules. Numbers of single molecule proteins analyzed are shown in parentheses. The distances (R) were obtained from E* using Equation 2.

Mutants	Ligand-free	Mg-IDP	K+	K+/Mg-IDP	Pi
R169K/G219C
E* (%; n)	58.6 ± 9.0 (68)	58.5 ± 7.7 (65)	58.3 ± 8.1 (74)	56.3 ± 7.3 (70)	57.9 ± 8.7 (75)
R (Å)	52.8	52.9	53.0	53.7	53.1
R169K/S642C
E* (%; n)	90.1 ± 4.3 (68)	89.6 ± 5.2 (71)	90.3 ± 4.9 (67)	90.2 ± 4.3 (71)	89.4 ± 4.7 (79)
R (Å)	38.8	39.1	38.6	38.7	39.3