TABLE 3.

Comparison of Fe²⁺ and Co²⁺ dissociation constants of MtCtpD and C318A and H642A variants

MtCtpD	Fe2+		Co2+
	KDa	na	KD	n
	μm		μm
WT	0.12 ± 0.04	1.32 ± 0.11	0.33 ± 0.04	1.26 ± 0.04
C318A	4.01 ± 0.89	0.74 ± 0.07	0.28 ± 0.08	1.20 ± 0.05
H642A	0.28 ± 0.08	1.14 ± 0.10	0.34 ± 0.05	1.33 ± 0.14

^a Values obtained by fitting curves resulting from competitive metal binding with mag-fura-2 (Fig. 7). Values are the mean ± S.D. (n = 3).