. Author manuscript; available in PMC: 2008 Sep 8.

Published in final edited form as: Biochemistry. 2006 Jan 31;45(4):1242–1254. doi: 10.1021/bi051669r

Table 1.

α-Helical Content and Thermodynamic Parameters of WT and Mutant Forms of Lipid -Free ApoA-I Determined by Far-UV CD ^a.

apoA-I	α-helix ^d (%)	# residues		T^d_m^f (°C)	T_m^f (°C)	ΔH_v^f (kcal/mol)	ΔG_D^o^g (kcal/mol)	m^g [kcal (mol of A-I)^-1 (mol of GndHCl)^-1]	D_1/2^g, (M)
apoA-I	α-helix ^d (%)	in protein	in helix ^e	T^d_m^f (°C)	T_m^f (°C)	ΔH_v^f (kcal/mol)	ΔG_D^o^g (kcal/mol)	m^g [kcal (mol of A-I)^-1 (mol of GndHCl)^-1]	D_1/2^g, (M)
WT ^b	58 ± 2	248	144	62 ± 0.5	60 ± 0.5	41 ± 1	2.5 ± 0.1	2.5 ± 0.1	1.0 ± 0.05
apoA-I[D102A/D103A] ^b	54 ± 2^*	248	134 (-10)	58 ± 1^**	56 ± 1^**	28 ± 2^***	2.1 ± 0.1^*	2.2 ± 0.2	0.9 ± 0.03
apoA-I[R116V/ K118A] ^b	57 ± 4	248	141 (~0)	60 ± 0.5^*	58 ± 0.5^*	35 ± 2^*	2.4 ± 0.2	2.4 ± 0.1	1.0 ± 0.04
apoA-I[R160V/H162A] ^b	59 ± 4	248	146 (~0)	63 ± 1	61 ± 1	32 ± 2^***	2.1 ± 0.2	2.2 ± 0.2	0.9 ± 0.05
apoA-I[Δ(61-78)] ^b	50 ± 3^**	230(-18)	115 (-29)	-	47± 1^***	16 ± 1^***	1.0 ± 0.2^***	1.3 ± 0.2^***	0.7 ± 0.05^**

WT ^c	59 ± 2	249	147	59 ± 0.5	59± 1	48 ± 1	3.0 ± 0.2	3.0 ± 0.2	1.0 ± 0.05
apoA-I[E110A/E111A] ^c	52 ± 2^**	249	129(-18)	54 ± 1^**	54 ± 0.5^**	30 ± 1^**	2.0 ± 0.2^*	2.0 ± 0.2^*	1.0 ± 0.00
apoA-I[Δ(121-142)] ^c	61 ± 1	227(-22)	139(-8)	60 ± 0.5	60 ± 1	53 ± 1^*	3.7 ± 0.2^*	3.4 ± 0.2	1.1± 0.03

Values are the average ± S.D. from 3 to 6 experiments for two or three independent preparations of each protein. Significance of differences from the value for WT:

p<0.05,

^**

p<0.01,

^***

p<0.005.

Proteins expressed in the baculovirus expression system.

Protein expressed in the adenovirus expression system.

Estimated from the value [Θ₂₂₂] at 25 °C. The values are the average ± S.D. from 10 to 16 measurements for each protein.

The number of residues in the helical conformation as estimated by multiplying the number of residues in the protein by its α-helical content. Values in parentheses show changes in the number of residues as compared to WT.

Parameters determined from the thermal unfolding curves. T^d_m is a maximum of the first derivative function d[Θ₂₂₂]/dT; the melting temperature, T_m, and effective enthalpy, ΔH_v, were determined from van’t Hoff analysis of the thermal unfolding curves.

The conformational stability, ΔG_D^o, midpoint of chemical denaturation, D_1/2, and m values were determined by the linear extrapolation method from the GdnHCl-induced unfolding curves.