Table 1.
Binding and thermodynamic parameters for annexin a5 titrations with 60:40 POPC/POPS and varying Ca2+
| Ca2+ binding |
Membrane bindinga |
|||
|---|---|---|---|---|
| Without membrane | With membrane, high affinity | With membrane, low affinity | With saturating Ca2+ present | |
| N | 5.0 ± 0.4 | 2.0 ± 0.1 | 3.0 ± 0.1 | z = 46.5 ± 0.1 |
| K (M−1) | 3100 ± 300 | 410,000 ± 120,000 | 5800 ± 100 | 78,000 ± 4000 |
| KD (μM) | 330 ± 40 | 2.4 ± 1.0 | 170 ± 10 | 13 ± 1 |
| ΔH (kcal/mol) | −2.4 ± 0.2 | 3.8 ± 0.2 | −13.4 ± 0.4 | −17.3 ± 0.1 |
| TΔS (kcal/mol) | 2.2 ± 0.2 | 11.2 ± 0.3 | −8.5 ± 0.4 | −10.9 ± 0.1 |
| ΔG (kcal/mol) | −4.6 ± 0.1 | −7.4 ± 0.2 | −4.9 ± 0.1 | −6.4 ± 0.1 |
The reported error represents 95% confidence intervals.
a
The affinity for annexin to bind membrane in the absence of Ca2+ was calculated to be KL = (2.1 ± 0.3) × 101 M−1 (KD,L = 50 ± 20 mM).