. Author manuscript; available in PMC: 2009 Jan 7.

Published in final edited form as: Biochemistry. 2008 Dec 16;47(50):13318–13325. doi: 10.1021/bi801675a

Table 1.

Binding Constants, Free Energy Changes, Electron Transfer Rates and Activation Energies for Native and Mutant RCs.^a and Solvent Accessible Surface Area of the Mutated Residue^b.

RC strain	K_A	*ΔΔG_B*	k_e	E_a	k₂	SASA^b
	(μM⁻¹)	(meV)	(10⁶ s⁻¹)	(meV)	(10⁹ s⁻¹M⁻¹)	A²
Native	4.0	0	1.00	65	1.7	-
NA(M188)	5.0	−6	0.93	21	2.0	23
QA(L258)	1.7	22	0.82	5	1.4	14
NA(M187)	0.5	53	0.26	21	2.0	9
Triple H-bond	0.22	74	0.10	35	1.5	-
YF(L162)	0.23	73	0.25	-	0.8	-
YF(L162)/NA(M187)	0.33	64	0.50	-	1.2	-

K_A is the binding constant, k_e the first order electron transfer rate constant, k₂ the second order electron transfer rate constant, ΔΔG_B the change in the binding free energy with respect to the native RC, E_a the activation energy for the first order electron transfer rate

SASA is the solvent accessible surface area of the mutated amino acid side chain in the Native cyt:RC complex. Statistical uncertainties: measure rate constants are ± 10%, K_A ± 10%, E_a ± 20meV, ΔΔG_B ± 4 meV,.