Table 1.

Goodness of Fit of ENSEMBLE Structures to Experimental Constraints

Restraint	Target Energy Term	Target Energy Value	Calculated Energy Value
K2 alone
RDC	$\frac{1}{4}N$	15.000	1.326
PRE	$\frac{1}{4}N$	1.733	0.964
ACCESS	$1\%\sum _N\left({\text{low}}^2+{\text{up}}^2\right)$	6.641	5.099
R2	r	5.050	3.699
δC′	$\sum _N\frac{{\sigma }_N}{4}$	11.640	11.611
δCα	$\sum _N\frac{{\sigma }_N}{4}$	23.709	23.632
δCβ	$\sum _N\frac{{\sigma }_N}{4}$	9.944	9.490
δHN	$\sum _N\frac{{\sigma }_N}{4}$	1.414	1.146
δHα	$\sum _N\frac{{\sigma }_N}{4}$	1.130	0.110
K2 with SDS
RDC	$\frac{1}{4}N$	10.500	1.659
PRE	$\frac{1}{4}N$	1.402	1.108
R2	r	5.049	3.393
δC′	$\sum _N\frac{{\sigma }_N}{4}$	8.266	6.575
δCα	$\sum _N\frac{{\sigma }_N}{4}$	6.269	6.197
δCβ	$\sum _N\frac{{\sigma }_N}{4}$	7.321	6.299
δHN	$\sum _N\frac{{\sigma }_N}{4}$	1.458	1.310
δHα	$\sum _N\frac{{\sigma }_N}{4}$	0.336	0.331

Target energy functions are defined by Marsh and Forman-Kay (53). ACCESS, accessible surface area; R₂, transverse relaxation rate, δC′, carbonyl chemical shift; δCα, carbon chemical shift; δCβ, β-carbon chemical shift; δHN, amide proton chemical shift; δHα, α-proton chemical shift; N, value of the restraint; σ_N, average standard deviation of the restraint; r, correlation coefficient for fitting R₂. Energy term units are arbitrary.