. Author manuscript; available in PMC: 2010 Apr 12.

Published in final edited form as: Biochemistry. 2008 Dec 23;47(51):13470–13480. doi: 10.1021/bi801223n

Table 1.

Site-Specific Equilibrium Parameters

absorption	observed transition^a	pH_m	n	equilibrium transition^b
Met80	N ⇌ I₁	8.7 ± 0.4	1.0 ± 0.2	III ⇌ (3.5 + IV_a)
	I₁ ⇌ I₂	11.6 ± 0.3	0.37 ± 0.07	(3.5 + IV_a) ⇌ IV_b
	I₂ ⇌ A’	10.9 ± 0.8	1.0 ± 0.4	IV_b ⇌ (V + U)
Lys72	N ⇌ A	10.5 ± 0.1	0.7 ± 0.2	deprotonation
Lys73	N ⇌ I	10.5 ± 0.2	0.51 ± 0.06	(III + 3.5) ⇌ IV_a
Lys73	I ⇌ A	10.0 ± 0.9	0.4 ± 0.2	IV_a ⇌ (V + U)
Lys79	N ⇌ I	12 ± 1	0.35 ± 0.07	(III + 3.5) ⇌ IV_b
Lys79	I ⇌ A	9 ± 3	0.4 ± 0.5	IV_b ⇌ (V + U)
Leu68	N ⇌ A	12.7 ± 0.1	1.3 ± 0.4	V ⇌ U
695 nm	N ⇌ A	8.84 ± 0.01	1.18 ± 0.07	III ⇌ 3.5

Equilibrium parameters obtained from fits of the fractional concentrations corresponding to the folded (N), high pH, solvent-exposed (A), and any intermediate (I) signal using the linearized Yang and Honig model. For Met80, a four-state fit was applied corresponding to signals N, two intermediary signals I₁ and I₂, and the high pH, solvent-exposed signal was fit to the sum of two components, A = I₁ + A’ (see text).

Approximate assignments; see text and Supporting Information for details.