Table 2.

α-Helical Content, Thermodynamic Parameters, and ANS Binding for the ApoA-I Variants in Solution

	α-helixc (%)	Tmd (°C)	ΔHvd (kcal/mol)	ΔGD°e (kcal/mol)	Pf (relative units)
WT apoA-Ia	58 ± 2	60 ± 0.5	41 ± 1	2.5 ± 0.1	1.0
apoA-I[Δ(89–99)]a	52 ± 2g	48 ± 1i	9 ± 2i	1.7 ± 0.1h	0.8
apoA-I[Δ (61–78)]a	50 ± 3h	47 ± 1i	16 ± 1i	1.0 ± 0.2i	1.6
WT apoA-Ib	59 ± 2	59 ± 1	48 ± 1	3.0 ± 0.2	1.0
apoA-I[E110A/E111A]b	52 ± 2h	54 ± 0.5h	30 ± 1h	2.0 ± 0.2g	1.5

^aProteins were expressed in the baculovirus expression system.

^bProteins were expressed in the adenovirus expression system.

^cThe α-helical content was calculated from the mean residue ellipticity at 222 nm determined from the normalized far-UV CD spectra.

^dThe melting temperature (T_m) and van’t Hoff enthalpy (ΔH_v) were determined from van’t Hoff analysis of thermal unfolding curves monitored by CD.

^eThe conformational stability (ΔG_D°) was determined from the CD-monitored GdnHCl-induced unfolding.

^fThe ANS fluorescence intensity (I) is shown relative to the ANS intensity in the presence of WT apoA-I expressed in the baculovirus expression system.

^gp < 0.05, compared to the values for WT apoA-I expressed in the same expression system.

^hp < 0.01, compared to the values for WT apoA-I expressed in the same expression system.

ⁱp < 0.005, compared to the values for WT apoA-I expressed in the same expression system. The experimental data for WT apoA-I, apoA-I[Δ(61–78)], and apoA-I[E110A/E111A] can be found in ref 16.