Table 3.

Thermodynamic parameters and affinity data for Hb binding

Errors represent the standard deviation of four replicates.

	KD	ΔH0	ΔS0	ΔG0a	nb
	μm	kcal/mol	cal/mol·K	kcal/mol
Hb + αIsdHY642A	4.0 ± 0.6	−6.0 ± 0.5	4.6 ± 1.9	−7.4 ± 0.1	0.59 ± 0.03
Hb + αIsdHN2	7.5 ± 1.1	−10.3 ± 0.5	−11.1 ± 2.0	−7.0 ± 0.1	0.62 ± 0.04
Hb + αIsdHLN3(Y642A)	≥mm	Endothermic	Positive	NDc	ND

^a Samples were in buffer containing 20 mm sodium phosphate, 150 mm NaCl, 450 mm sucrose, pH 7.5, 298 K.

^b n refers to the molar ratio protein/Hb.

^c ND means not determined.