TABLE 4

Thermodynamics of IP3 and adenophostin A binding to the NT and IBC

From the effects of temperature on IP3 and adenophostin A binding to the IBC and NT in CLM (Table 3, Fig. 4, and Supplemental Fig. 6), ΔG was determined (ΔG = R · T lnKD) and thereby ΔH and ΔS (eq. 3, assuming ΔC = 0). A similar analysis in which ΔC was not fixed to 0 provided indistinguishable results (Supplemental Table 1). −TΔS is also shown for 296 K. Results are means ± S.E.M., from three separate van't Hoff plots.

ΔGaΔHΔSTΔSa
kJ/molJ/mol·KkJ/mol
IP3
    NT−37.1 ± 0.1−37.0 ± 1.10.9 ± 3.7−0.3 ± 1.1
    IBC−43.2 ± 0.1−36.8 ± 0.321.3 ± 1.5−6.3 ± 0.4
Adenophostin A
    NT−43.5 ± 0.02−32.1 ± 1.135.6 ± 3.7−10.5 ± 1.1
    IBC−49.4 ± 0.2−21.9 ± 1.093 ± 3.6−27.5 ± 1.1