Table 1.

O₂-affinities and allosteric properties of native and recombinant Hbs of alligator and human

	Native alligator Hb		Unacetylated alligator rHb		Acetylated alligator rHb		Native human Hb		Unacetylated human rHb		Acetylated human rHb
Treatments	P50	n50	P50	n50	P50	n50	P50	n50	P50	n50	P50	n50
Stripped	3.80 ± 0.06	1.70 ± 0.1	3.77 ± 0.27	1.10 ± 0.01	3.54 ± 0.38	1.41 ± 0.17	8.43 ± 0.09	1.69 ± 0.10	9.05 ± 0.74	2.11 ± 0.10	8.95 ± 1.27	1.83 ± 0.04
+KCl	11.82 ± 0.10	1.40 ± 0.01	6.95 ± 0.08	1.27 ± 0.01	6.03 ± 0.20	1.35 ± 0.05	16.90 ± 0.70	2.15 ± 0.09	17.74 ± 0.46	2.15 ± 0.05	16.00 ± 0.06	2.13 ± 0.01
+OP	5.12 ± 0.38	1.55 ± 0.06	3.97 ± 0.22	1.22 ± 0.04	3.52 ± 0.09	1.19 ± 0.01	14.42 ± 0.72	2.21 ± 0.09	10.25 ± 0.58	2.14 ± 0.05	11.20 ± 0.38	2.79 ± 0.26
+KCl +OP	11.24 ± 0.26	1.40 ± 0.01	7.13 ± 0.14	1.25 ± 0.01	5.61 ± 0.09	1.23 ± 0.02	17.25 ± 0.69	2.20 ± 0.22	17.40 ± 0.18	2.02 ± 0.06	15.69 ± 0.12	2.30 ± 0.08
ΔlogP50
KCl – stripped	0.493		0.266		0.231		0.302		0.292		0.252
OP* – stripped	0.129		0.022		−0.002		0.233		0.054		0.097
(KCl + OP*) – stripped	0.471		0.277		0.200		0.311		0.284		0.244

Sensitivities to allosteric effectors are measured as the difference in the log-transformed P₅₀ values in the presence and absence of anions (Cl⁻ and organic phosphates), individually and in combination.

OP* organic phosphate (ATP in experiments on alligator Hb, DPG in experiments on human Hb).