TABLE 2.

α-Helical content, thermodynamic parameters, and ANS fluorescence for lipid-free WT apoA-I and the apoA-I mutant forms

	α-Helixa(%)	Tmb(°C)	ΔHvb(kcal/mol)	Δ Gc  (kcal/mol)	mc[kcal (moles of apoA-I)−1 (moles of GdnHCl)−1]	D1/2c (M)	Id (relative units)	WMFd (nm)
WT apoA-I	58 ± 2	63 ± 1	43 ± 2	4.3 ± 0.1	4.0 ± 0.2	1.0 ± 0.05	1.0	474
apoA-I[K107A]	58 ± 3	62 ± 1	46 ± 2	4.6 ± 0.2	4.5 ± 0.1e	1.0 ± 0.0	0.8	477 (+3)
apoA-[K107del]	55 ± 1	57 ± 2e	29 ± 1g	3.0 ± 0.1e	3.7 ± 0.1	0.8 ± 0.0f	1.5	468 (−6)

Values are mean ± SD from at least three experiments.

^aEstimated from the [Θ₂₂₂] at 25°C.

^bThe 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.

^cThe conformational stability, ΔG_D⁰, m-values and midpoint of chemical denaturation, D_1/2, were determined by the linear extrapolation method from the curves for CD-monitored GdnHCl-induced unfolding.

^dParameters of ANS fluorescence were determined in the presence of WT apoA-I, apoA-I[K107A], or apoA-[K107del]. I, fluorescence intensity in relative units compared with the fluorescence in the presence of WT apoA-I.

^eP < 0.05 compared with the values for WT apoA-I.

^fP < 0.01 compared with the values for WT apoA-I.

^gP < 0.005 compared with the values for WT apoA-I.