TABLE 4.
O2 binding properties (mean ± SEM, n = 3) of stripped hemolysates from the BALB/c and MSM/s inbred strains (which are homozygous for the Hbbd and Hbbp β-globin haplotypes, respectively)
| Strain (β-haplotype) | Conditions | P50 (torr) | n50 |
|---|---|---|---|
| BALB/c (Hbbd) | Stripped | 8.44 ± 0.09 | 2.46 ± 0.05 |
| DPG | 11.88 ± 0.17 | 2.65 ± 0.09 | |
| KCl | 16.27 ± 0.30 | 2.68 ± 0.12 | |
| DPG + KCl | 17.53 ± 0.27 | 2.78 ± 0.13 | |
| MSM/s (Hbbp) | Stripped | 8.76 ± 0.04 | 2.40 ± 0.02 |
| DPG | 11.64 ± 0.07 | 2.50 ± 0.04 | |
| KCl | 17.74 ± 0.06 | 2.67 ± 0.02 | |
| DPG + KCl | 17.03 ± 0.27 | 2.56 ± 0.09 |
P50 and n50 values indicate the O2 tensions and cooperativity coefficients at half-saturation, respectively. O2 equilibria were measured in 0.1 m HEPES buffer at pH 7.40, 37°, in the absence of allosteric cofactors (stripped hemolysates), in the presence of DPG alone, in the presence of KCl alone, and in the presence of both cofactors [(Cl−), 0.10 m; DPG/Hb tetramer ratio, 2.0; (Heme), 0.16 mm].