Table 1.

Microscopic rate constants and kinetic m^‡ values obtained from the global kinetic analysis of HIV-PR* at pH 6.0 and 25 °C.

HIV-PR*a
	Value	Errorf	Units
$\mathrm{U}\underset{k_u}{\overset{k_f}{\leftrightarrows }}\mathrm{M}$
kf	9.44 × 10−2	± 0.06 × 10−2 ± 0.40 × 10−2 g	s−1
m‡f	0.72	± 0.01	kcal (mol monomer)−1M−1
ku	1.59 × 10−2	± 0.09 × 10−2 ± 1.4 × 10−2 g	s−1
m‡u	−0.18	± 0.01	kcal (mol monomer)−1M−1
ΔG°(U/M)b	−1.05	± 0.04 ± 0.52 g	kcal (mol monomer)−1
m (U/M)c	0.89	± 0.02	kcal (mol monomer)−1M−1
$2\mathrm{M}\underset{k_d}{\overset{k_a}{\leftrightarrows }}{\mathrm{N}}_2$
ka	1.02 × 106	± 0.06 × 106 ± 0.50 × 106 g	M−1 s−1
ma‡	0.58	± 0.02	kcal (mol dimer)−1 M−1
kd	2.15 × 10−3	± 0.02 × 10−3 ± 0.05 × 10−3 g	s−1
md‡e	−0.14	± 0.01	kcal (mol dimer)−1 M−1
ΔG°(2M/N2)b	−11.83	± 0.04 ± 0.29 g	kcal (mol dimer)−1
m (2M/N2)c	0.72	± 0.02	kcal (mol dimer)−1 M−1
$2\mathrm{U}\underset{{k^{\ast }}_u}{\overset{{k^{\ast }}_f}{\leftrightarrows }}2\mathrm{M}\underset{k_d}{\overset{k_a}{\leftrightarrows }}{\mathrm{N}}_2$
ΔG°kin(2U/N2)d	−13.93	± 0.08 ± 1.08 g	kcal (mol dimer)−1
mkin(2U/N2)e	2.50	± 0.04	kcal (mol dimer)−1 M−1

^a96 fluorescence kinetic traces were globally fit to the model shown in Scheme 1, 2U ⇆ 2M ⇆ N₂. The unimolecular rate constants $k_f^{\ast }$ and $k_u^{\ast }$ in Scheme 1, expressed with respect to a dimeric reference state, are related to the unimolecular rate constants k_f and k_u in the monomer reference state in the following way: k_f=(k_f*)^½ and k_u=(k_u*)^½. The association and dissociation rate constants (k_a and k_d) are always reported with respect to a dimer reference state. Buffer conditions were 100 mM sodium phosphate, pH 6.0, and 0.2 mM EDTA at 25 °C. Protein concentrations ranged from 0.1-12 μM.

^bCalculated according to ΔG°_(U/M) = −RTlnK = −RTln(k_f/k_u) and ΔG°_(2M/N2) = −RTlnK = −RTln(k_a/k_d).

^cCalculated according to m^‡_(U/M) = | m^‡_f| + | m^‡_u| and m^‡_(2M/N2) = | m^‡_a| + | m^‡_d.|.

^dGlobal stability obtained from the kinetic data, calculated according to ΔG°_kin(2U/N2) = 2ΔG°_(U/M) + ΔG°_(2M/N2).

^em value obtained from the kinetic data, calculated according to m^‡_kin(2U/N2) = 2| m^‡_f | + 2| m^‡_u| + | m_a^‡| + | m_d^‡_d.|.

^fErrors are standard errors from the fit unless otherwise indicated.

^gErrors obtained at the 68% confidence interval from a rigorous error analysis.