. Author manuscript; available in PMC: 2014 Jul 31.

Published in final edited form as: J Am Chem Soc. 2013 Jul 18;135(30):11181–11192. doi: 10.1021/ja403917z

Table 3.

Kinetic and thermodynamic parameters for [p-Ac-Phe]RNase S compared to those of wild-type RNase

	Wild-type RNase ^a	[p-Ac-Phe]RNase S
Catalytic Activity ^b
k_cat / s⁻¹	2.8 ± 0.1	0.8 ± 0.03
K_M / mM	1.25 ± 0.1	1.37 ± 0.2
R²	0.994	0.991
S-peptide Binding Thermodynamics ^c
K_D	110 ± 20 nM ^d	12.7 ± 1 μM
ΔG°	−9.5 ± 0.1 kcal/mol ^d	−6.7 ± 0.1 kcal/mol
ΔH°	−39.3 ± 0.6 kcal/mol ^d	−16.7 ± 0.1 kcal/mol
ΔS°	−100 cal/(mol K) ^d	−33.6 cal/(mol K)

Wild-type RNase refers to single-chain RNase A for activity measurements and the split-protein RNase S for binding measurements.

Michaelis-Menton kinetics for the hydrolysis of cyclic cytidine monophosphate. See Figure S3 for full data and analysis.

Thermodynamics for the binding of S-peptide to S-protein to form RNase S at 25 °C as determined by isothermal titration calorimetry. See Figure S6 for full data and analysis.

Data from Ref. 38.