Table 3.

Thermodynamic and kinetic parameters describing unfolding and CO binding of Fe²⁺ cyt c in the absence of denaturant (pH 7, 20 °C) predicted on the basis of Scheme 2

Transition (states i ⬄ j)	forward rate (s−1) (i→j)	back rate (s−1) (j→i)	ΔGij (kcal mol−1)
N ⬄ Ma	4.0×10−3	8.3×10−4	9.8
M ⬄ Ub	−	−	12.2
M-CO ⬄ U-COb	−	−	11.3
M ⬄ M-COc	6.4	2.9×10−4	−5.8
U ⬄ U-COc	350	3.4×10−3	−6.7

^aThe forward rate, k_NM, increases with GuHCl concentration (kinetic m-value m_NM = 0.6 kcal mol⁻¹ M⁻¹) while the back rate, k_MN, is assumed to be independent of denaturant (see ref.25).

^bKinetic parameters describing the folding and unfolding transitions of Fe²⁺ cyt c in the presence and absence of CO will be reported elsewhere (Maki, Latypov, Hagen & Roder, in preparation).

^cThe CO binding rates are apparent rate constants at 1 mM CO. CO binding and dissociation rates are independent of GuHCl concentrations, except for the M-CO -> M + CO transition, which has a small negative m-value (−0.15 kcal mol⁻¹ M⁻¹; Figure 10(b)).