Table 2.

Apparent Zinc-Binding Dissociation Constants for Peptoids and FRET Efficiencies for the Zinc-Bound State of Peptoids^a

peptoid	apparent kd (M)	ΔΔGzn (kcal/mol)	FRET efficiency
2_FQ	(1.2 ± 0.5) × 10−6	0	0.86 ± 0.01
3_FQ	(5.8 ± 1.0) × 10−6	0.9	0.85 ± 0.01
4_FQ	(8.9 ± 2.2) × 10−6	1.0	0.68 ± 0.01
5_FQ	(6.5 ± 1.4) × 10−6	1.2	0.78 ± 0.01
6_FQ	(8.5 ± 3.0) × 10−5	2.5	0.66 ± 0.02
7_FQ	(3.7 ± 1.5) × 10−6	0.7	0.79 ± 0.01
8_FQ	∼0.3 × 10−9 b	−4.9	0.88 ± 0.01
9_FQ	∼0.4 × 10−9 b	−4.7	0.81 ± 0.02
11_FQ	(8.9 ± 3.4) × 10−7	−0.2	0.77 ± 0.01
12_FQ	(7.8 ± 2.8) × 10−7	−0.3	0.68 ± 0.01

^aThe free energy difference of the zinc-bound state (ΔΔG _zn) was calculated from ΔΔG _zn = −RT ln (k_d_ref/k_d_sample). R is the gas constant and T is temperature. We took the k_d of 2_FQ as the reference k_d.

^bZinc-binding dissociation constants were obtained from the competition assay with EGTA (Figure 6).