Table 1.

Binding affinities of wild-type hCypA to SARS_NP and its mutants and wild-type SARS_NP to hCypA and its mutants

NP mutation	kon (M−1 s−1)	koff (s−1)	KD (nM)	ΔΔGbind (kcal/mol)
				Experimentala	Predictedb
hCypA binding affinity
Wild type	1.17 ± 0.005 × 104	7.10 ± 0.032 × 10−5	6.04	0.0	0.0
Trp302Ala	1.43 ± 0.053 × 104	3.41 ± 0.088 × 10−3	238	2.18	2.00
Ile305Ala	7.67 ± 0.094 × 103	9.86 ± 0.075 × 10−4	129	1.81	0.50
Gln307Ala	1.59 ± 0.032 × 104	1.99 ± 0.093 × 10−4	12.6	0.44	3.95
Gln307Asp	1.12 ± 0.088 × 104	2.25 ± 0.026 × 10−4	20.1	0.71	11.75
hCypA mutation	$k_{\mathrm{on}}^{\prime }$ (M−1 s−1)	$k_{\mathrm{off}}^{\prime }$ (s−1)	$K_{\mathrm{D}}^{\prime }$ (nM)	ΔΔGbind (kcal/mol)
				Experimentalc	Predictedd
SARS_NP binding affinity
Wild type	854 ± 24.5	1.36 ± 0.066 × 10−4	159	0.0	0.0
Arg55Ala	715 ± 4.33	5.14 ± 0.018 × 10−4	719	0.90	1.13
Arg55Asp	4.74 ± 0.019 × 103	1.02 ± 0.094 × 10−3	215	0.18	4.02
Gln63Ala	7.31 ± 0.087	2.72 ± 0.018 × 10−4	37,200	3.23	4.95
Trp121Phe	7.99 ± 0.096	2.11 ± 0.012 × 10−4	26,300	3.03	0.78
Arg69Ala	5.10 ± 0.028 × 103	3.80 ± 0.076 × 10−4	74.6	−0.45	−0.89
Arg69Lys	123 ± 2.53	3.89 ± 0.039 × 10−4	3160	1.77	0.48

^aRelative binding free energies of hCypA–SARS_NP mutants binding relative to the hCypA–SARS_NP binding calculated from the SPR dissociation constants (K_Ds).

^bPredicted relative binding free energies of hCypA–SARS_NP mutants binding relative to the hCypA–SARS_NP binding calculated by the MM/PBSA method.

^cRelative binding free energies of SARS_NP-hCypA mutants binding relative to the SARS_NP–hCypA binding calculated from the SPR dissociation constants $(K_{\mathrm{D}}^{\prime }\mathrm{s})$.

^dPredicted relative binding free energies of SARS_NP–hCypA mutants binding relative to the SARS_NP–hCypA binding calculated by the MM/PBSA method.