TABLE 5.

Thermodynamic parameters for the cleavage of HHL, Z-FHL and angiotensin I by ACE constructs

Shown are thermodynamic parameters associated with the cleavage of HHL, Z-FHL, and angiotensin I by the C-domain, N-domain, and a number of C-domain mutant constructs. Values were determined at 0 and 20 mm NaCl (including 300 mm for the C-domain with HHL). Values are shown as the mean of three separate determinations of ΔG, ΔH, and −TΔS along with S.E.

Construct	Substrate	[NaCl]	ΔHint	ΔG	−TΔS
		mm	kcal mol−1	kcal mol−1	kcal K−1 mol−1
N-domain	HHL	0	2.48 ± 0.03	−5.04 ± 0.02	−7.52 ± 0.05
		20	2.59 ± 0.01	−6.93 ± 0.00	−9.52 ± 0.01
	Z-FHL	0	2.25 ± 0.01	−6.71 ± 0.01	−8.96 ± 0.01
		20	2.80 ± 0.06	−8.50 ± 0.02	−11.29 ± 0.08
	Angiotensin I	0	2.80 ± 0.06	−6.46 ± 0.01	−11.29 ± 0.08
		20	2.71 ± 0.10	−7.81 ± 0.05	−10.52 ± 0.10
C-domain	HHL	0	2.37 ± 0.07	−4.19 ± 0.01	−6.56 ± 0.07
		20	2.73 ± 0.03	−6.93 ± 0.01	−9.66 ± 0.03
		300	2.60 ± 0.01	−8.33 ± 0.01	−10.93 ± 0.01
	Z-FHL	0	2.27 ± 0.03	−7.30 ± 0.01	−9.57 ± 0.04
		20	2.70 ± 0.04	−9.06 ± 0.02	−11.80 ± 0.03
	Angiotensin I	0	2.16 ± 0.07	−6.44 ± 0.04	−8.60 ± 0.10
		20	2.19 ± 0.04	−7.53 ± 0.00	−9.72 ± 0.04
R186H	HHL	0	2.25 ± 0.01	−3.75 ± 0.01	−6.00 ± 0.01
		20	2.72 ± 0.02	−6.77 ± 0.01	−9.49 ± 0.02
	Z-FHL	0	2.53 ± 0.06	−6.92 ± 0.02	−9.45 ± 0.08
		20	2.74 ± 0.08	−9.22 ± 0.05	−11.95 ± 0.07
	Angiotensin I	0	2.27 ± 0.04	−6.03 ± 0.01	−8.30 ± 0.03
		20	2.19 ± 0.01	−6.97 ± 0.02	−9.16 ± 0.02
E403R	HHL	0	2.62 ± 0.01	−5.21 ± 0.01	−7.82 ± 0.02
		20	2.93 ± 0.05	−7.76 ± 0.03	−10.69 ± 0.04
	Z-FHL	0	2.41 ± 0.03	−7.77 ± 0.01	−10.18 ± 0.04
		20	2.83 ± 0.10	−8.85 ± 0.01	−11.67 ± 0.11
	Angiotensin I	0	2.63 ± 0.05	−6.73 ± 0.05	−9.35 ± 0.10
		20	2.75 ± 0.11	−7.21 ± 0.03	−9.97 ± 0.10
R522Q	HHL	0	2.48 ± 0.03	−4.46 ± 0.02	−6.94 ± 0.05
		20	2.65 ± 0.16	−4.90 ± 0.02	−7.54 ± 0.18
	Z-FHL	0	2.38 ± 0.05	−8.41 ± 0.02	−10.79 ± 0.06
		20	2.51 ± 0.06	−8.24 ± 0.05	−10.75 ± 0.01
	Angiotensin I	0	2.28 ± 0.01	−7.30 ± 0.01	−9.59 ± 0.02
		20	2.36 ± 0.11	−7.45 ± 0.04	−9.80 ± 0.15
R522K	HHL	0	2.29 ± 0.05	−4.47 ± 0.02	−6.76 ± 0.07
		20	2.24 ± 0.04	−4.46 ± 0.01	−6.69 ± 0.04
	Z-FHL	0	2.22 ± 0.02	−7.58 ± 0.01	−9.81 ± 0.03
		20	2.78 ± 0.04	−7.58 ± 0.02	−10.36 ± 0.05
	Angiotensin I	0	2.21 ± 0.04	−5.39 ± 0.02	−7.24 ± 0.02
		20	1.85 ± 0.00	−6.39 ± 0.01	−8.60 ± 0.04