Table 1.

Measured fluorescence lifetimes and transfer efficiencies of the three experimental systems. The last column presents the corresponding calculated transfer efficiencies of the presented systems.

Sample	$R_0(\AA )$	$\tau (\mathrm{ns})$ Amplitude	$<\tau >(\mathrm{ns})$	${\chi }^2$	Measured transfer	Calculated
Oligo-Donor	—	0.20 (0.171)	3.179	0.933	—	—
		1.38 (0.197)
		3.45 (0.632)
Donor-DL649	71.5	0.20 (0.180)	3.029	0.935	0.055	0.070
		1.35 (0.207)
		3.31 (0.613)
Donor plus	61.0	0.20 (0.184)	2.893	0.944	0.09	0.081
Avidin-DL750		1.33 (0.223)
($A=8$)		3.19 (0.593)
Donor plus	71.5	0.20 (0.203)	2.793	0.928	0.12	0.123
Avidin-DL649		1.31 (0.245)
($A=4.5$)		3.13 (0.552)
Donor-plus	71.5	0.20 (0.211)	2.724	0.925	0.143	0.156
Avidin-DL649		1.36 (0.257)
($A=6$)		3.08 (0.532)

$A$: number of labeled acceptors. Calculation are based on a distance of 110 Å for DL649, a distance of closest approach of 105 Å for systems with avidin (100 Å $\mathrm{DNA}+\mathrm{donor}$), and a 55 -Å diameter of the labeled protein.