. Author manuscript; available in PMC: 2017 Oct 19.

Published in final edited form as: Biochemistry. 2017 May 31;56(23):2950–2966. doi: 10.1021/acs.biochem.6b01187

Table 3.

Parameters for pH-Dependent Transitions in Horse Heart Ferricytochrome c

	Ligand Exchange	Region Monitored	pK_a	n
WT^a	His/H₂O → His/Met		2.5	1.14
	His/Met → His/Lys		9.35	1.0
T49V^b	His/H₂O → His/Met	Soret	3.3 ± 0.1	1.0 ± 0.1
		CT	3.0 ± 0.1	0.9 ± 0.1
	His/Met → His/Lys	Soret	6.8 ± 0.1	1.0 ± 0.1
		CT	6.7 ± 0.1	1.0 ± 0.1
Y67R/M80A^b	His/H₂O → His/Lys	Soret	5.6 ± 0.1	1.0 ± 0.1
		CT	5.6 ± 0.1	1.0 ± 0.1
M80A^b	His/H₂O → His/OH⁻	Soret	6.1 ± 0.1^c	0.9 ± 0.1

From ref. 13, performed at 20 °C.

Performed at 22 ± 2 °C.

A similar value has been reported in studies of semisynthetic M80A (ref. 50).