TABLE 2.

YC-1, PF-25 and BAY 41-2272 Dissociation Constants for sGC Proteins (μM).

	−NO/CO			+CO			+NO
Protein	KdYC-1	KdPF-25	KdBAY	KdYC-1′	KdPF-25′	KdBAY′	KdPF-25′
Ms sGC-NT13	21 ± 5a	155 ± 11a	17 ± 3b	1.1 ± 0.3a	3.0 ± 0.3a	0.08 ± 0.01e
				0.8 ± 0.1d	2.8 ± 0.2d
Ms sGC-NT21	9.3 ± 0.8a	73 ± 21a	2.0 ± 0.5a	0.67 ± 0.06a	3.8 ± 1.4a	0.03 ± 0.01a	11 ± 2c
		153 ± 5c		0.6 ± 0.1e	0.9 ± 0.3d	0.09 ± 0.02e
Ms sGC β1(1–380)		92 ± 5c					7 ± 1c
Ms sGC α1 PAS		N.B.c					N.B.c
Bt sGC (full length)	52f			~8h
	~20g

^aFrom global fitting of multidimensional titration data (see text). For Ms sGC-NT13, titration was in a 1 cm cuvette with 1 μM protein. For Ms sGC-NT21, titration was in a 10 cm cuvette with 0.1 μM protein. Values are the mean and standard deviation of three independent measurements. Values for K_d^YC-1′ were obtained using the cooperativity factors shown in Table 3.

^bEstimated assuming linked equilibria: (K_d^CO/K_d^CO′) K_d^BAY′.

^cFrom SPR (see text). Values in the absence of NO were fitted with calculated R_max and those in the presence were fitted with a floating R_max. Errors are from the fitting. N.B.: No binding.

^dFrom fitting of Soret shift (1 cm cuvette). Values are the mean and standard deviation of 3–5 independent measurements. For YC-1, 1 μM protein was used. For PF-25, both 1 and 0.5 μM protein was used.

^eFrom fitting of Soret shift (1 and 10 cm cuvette). Values are the mean and standard deviation of 3–10 independent measurements. For YC-1 (10 measurements), measurements with protein concentrations of 0.1 (10 cm cuvette), and 0.5 and 1.0 μM (1 cm cuvette) were included. For BAY 41-2272 (3 measurements), protein concentrations of 0.05 and 0.1 μM were included (10 cm cuvette).

^fFrom reference ³², measured in the presence of Mn²⁺.

^gFrom reference ²⁴, EC₅₀ value for stimulating bovine sGC in the absence of NO or CO.

^hFrom reference ⁵¹, measured in the presence of GTP.