Table 1.

Bcl-2ΔTM homo- or hetero-association with various Bax peptides^f .

Ligand	rFreea	rBoundb	Rc	Kd (μM)d
Bcl-2ΔTM	0.015 ± 0.005	0.101 ± 0.009	1.9 ± 0.1	0.25 ± 0.05
CF-H2	0.043 ± 0.004	0.15 ± 0.02	1.2 ± 0.1	2.4 ± 0.5
H2-H3e	0.043 ± 0.004	0.15 ± 0.02	1.2 ± 0.1	0.6 ± 0.2
H2-H3 G67Re	0.043 ± 0.004	0.15 ± 0.02	1.2 ± 0.1	No binding
H2e	0.043 ± 0.004	0.15 ± 0.02	1.2 ± 0.1	2.8 ± 0.6

^aThe anisotropy of free ligand, i.e., Trp anisotropy of monomeric Bcl-2ΔTM in the homo-association (r_M in Eq. 4), or CF anisotropy of free CF-H2 in the hetero-association (r_F in Eq. 7).

^bThe anisotropy of bound ligand, i.e., Trp anisotropy of dimeric Bcl-2ΔTM in the homo-association (r_D in Eq. 4), or CF anisotropy of Bcl-2ΔTM-bound CF-H2 in the hetero-association (r_B in Eq. 7).

^cThe intensity ratio of bound to free ligand, i.e., the Trp intensity ratio of dimeric to monomeric Bcl-2ΔTM in the homo-association (R in Eq. 4), or the CF intensity ratio of Bcl-2ΔTM-bound to free CF-H2 in hetero-association (R₁ in Eq. 7).

^dThe equilibrium dissociation constant for the homo-association (K_d in Eq. 3), or the hetero-association with either CF-H2 (K₁ in Eq. 6) or unlabeled H2-H3, H2-H3 G67R or H2 (K_u in Eq. 9–13).

^eCF-H2 is the additional ligand in the reaction, competing with the indicated ligand for binding to Bcl-2ΔTM.

^fAll fitting parameters were obtained by nonlinear squares fitting Eq. 3, 6 or 9 to the data from three independent titrations and reported as mean ± S.D.