Table 3.

Metal ion dissociation constants of Zn–TFIIIA and metallo-finger 3

Structure	Zn	Cd	Pb
TFIIIA	1×10−7a
	1×10−7b
F3	1.01±0.03×10−8c	1.98±0.04×10−8d	3.4±0.8×10−8e

^aZI as the competing ligand, 20 mM HEPES, pH 7.4 and 25 °C.

^bPAR as the competing ligand, 20 mM HEPES, pH 7.4 and 25 °C.

^cZI as the competing ligand, 20 mM Tris/Cl, 250 mM NaCl, pH 7.4 and 25 °C.

^dPAR as the competing ligand, 20 mM Tris/Cl, 250 mM NaCl, pH 7.4 and 25 °C.

^eMetal ion competition as described in Section 2, 20 mM Tris/Cl, 250 mM NaCl, pH 7.4 and 25 °C.