Table 2.
Effect of Nb on WT LacY affinity for α-NPGa
| Titrant (Syringe) | Titrand (Sample Cell) | Kd (μM) | ΔG [ΔΔG]b | ΔH [ΔΔH] | -TΔS [−TΔΔS] | N |
|---|---|---|---|---|---|---|
| (kJ/mol) | ||||||
| WT LacY | 28.8 (2.1c) | −25.9 (0.2) | −15.6 (3.4) | −10.3 (3.6) | 0.6 (0.1) | |
| WT:Nb-9036 | 0.3 (0.1) | −37.1 (0.6) | −54.3 (1.1) | 17.2 (0.5) | 0.5 (0.1) | |
| [−11.2**] | [−38.7**] | [27.5*] | ||||
| α-NPG | WT:Nb-9065 | 5.7 (0.1) | −30.0 (0.1) | −51.0 (1.8) | 21.0 (1.7) | 0.5 (0.0) |
| [−4.1**] | [−35.4*] | [31.3*] | ||||
| Double-Trp mutant | 5.0 (0.5) | −30.3 (0.3) | −42.1 (0.0) | 11.8 (0.3) | 0.5 (0.0) | |
| Mutant:Nb-9036 | 0.3 (0.0) | −37.5 (0.4) | −71.7 (2.5) | 34.2 (2.9) | 0.6 (0.0) | |
| [−7.2**] | [−29.6**] | [22.4*] | ||||
| Mutant:Nb-9065 | 7.1 (0.6) | −29.4 (0.2) | −41.8 (1.05) | 12.43 (0.9) | 0.4 (0.0) | |
| [0.9ns] | [0.3ns] | [0.6ns] | ||||
a
Data are from Fig. 3;
b
Difference in the absence and presence of Nb;
c
s.e.m., number of tests = 2. N, stoichiometry;
ns
not statistically significant;
*
statistically significant;
**
very statistically significant.