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. Author manuscript; available in PMC: 2013 Oct 5.
Published in final edited form as: J Mol Biol. 2012 Jun 19;422(5):674–684. doi: 10.1016/j.jmb.2012.06.019

Table 1.

Salt-dependence of p27-Cdk2/cyclin A binding kinetics and thermodynamics.

NaCl (mM) ka (106M−1s−1) KD (nM) ΔG (kcal/mol) ΔH (kcal/mol) −TΔS (kcal/mol)
75 10.6 ± 0.1 1.1 ± 0.6 −12.3 ± 0.3 −50.3 ± 3.6 +38.0 ± 3.6
150 3.21 ± 0.01 1.3 ± 0.8 −12.2 ± 0.4 −49.5 ± 1.6 +37.3 ± 1.8
300 1.26 ± 0.01 0.5 ± 0.6 −12.9 ± 0.7 − 51.0 ± 4.2 +38.0 ± 4.3
600 0.894 ± 0.001 0.6 ± 0.3 −12.7 ± 0.5 −48.7 ± 3.3 +36.0 ± 3.7
1000 - 0.6 ± 0.4 −12.6 ± 0.3 −45.4 ± 1.8 +32.8 ± 2.1

The Gibbs free energy of binding ΔG was calculated from the dissociation constant, ΔG = RT ln KD, and the binding entropy from the binding free energy and enthalpy as −TΔS = ΔG–ΔH.