Table 1.

Dissociation constants between BCL-xL and p53 constructs or between BCL-xL, pre-incubated with p53 constructs, and BID BH3 peptide^*

	BCL-xL – p53 Kd (μM)		BID – BCL-xL Kd (nM)**
p53 construct	ITC	CSP	(free BCL-xL) 23±7
NTD	250±80	230±90	37±6
DBD	17±2***	30±20	7±2
TET	no binding	no binding	N.D.
N-D	30±20***	40±10	63±8
D-T	1.9±0.1***	N.D.	7±4
N-D-T	0.6±0.3***	1.2±0.6	35±4

^*Affinities were determined by isothermal titration calorimetry (ITC – average of two independent titrations; error range: s.e.m.; N.D.: not determined) or fitting of NMR chemical shift perturbation data (CSP - for BCL-xL – p53 binding only; error ranges indicate uncertainties of fit for curves obtained from average CSP of 10–15 well resolved resonances).

^**Measured by ITC, titration of BID BH3 into BCL-xL pre-incubated with the indicated p53 construct

^***Titration of BCL-xLΔLΔC