Table 4.

Kinetic Parameters for the Alkaline Transition and Imidazole Binding for Horse Heart Ferricytochrome c Variants

Variant	kf (s−1)	kb (s−1)	KC	pKH	pKH + pKc	${\mathrm{K}}_{\mathrm{D}}^{\mathrm{I}\mathrm{m}}$(M)	${\mathrm{k}}_{\mathrm{obs}}^{\mathrm{I}\mathrm{m}}$(s−1)
WT	10.5 ± 0.2a	0.048a	218 ± 4a	11.5 ± 0.1a	9.2 ± 0.1	9.5×10−2b	60 ±15
T49Vc	13.7 ± 0.9	0.11 ± 0.02	125 ± 24	9.1 ± 0.1d	7.0 ± 0.1	1.4×10−3	0.08 ± 0.01
Y67R/M80Ac	7.7 ± 1.9	0.78 ± 0.38	9.9 ± 5.4	6.9 ± 0.4d	5.9 ± 0.5	2.9×10−4	0.79 ± 0.05

^aFrom ref. 75, performed at 25.0 ± 0.1 °C.

^bCalculated from values in ref. 44.

^cPerformed at 22 ± 2 °C.

^dDetermined from the fit of the data in Figure 11.