Hemoglobin Dallas (alpha 97(G4)Asn-->Lys): functional characterization of a high oxygen affinity natural mutant.
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Lendaro E, Ippoliti R, Brancaccio A, Bellelli A, Vallone B, Ivaldi G, Sciarratta GV, Castello C, Tomova S, Brunori M, et al.
Hemoglobin Dallas (alpha 97(G4)Asn-->Lys): functional characterization of a high oxygen affinity natural mutant.
Biochim Biophys Acta. 1992 Oct 13;1180(1):15-20.
- PubMed ID
- 1390940 [ View in PubMed]
- Abstract
Hemoglobin Dallas, an alpha-chain variant with a substitution of lysine for asparagine at position 97(G4), was found to have increased oxygen affinity (p1/2 = 1 mmHg at pH 7.3 and 20 degrees C), diminished cooperativity (n, the Hill coefficient = 1.7) and reduced Bohr effect (about 50%). Addition of allosteric effectors (such as 2,3-diphosphoglycerate, inositol hexakisphosphate and bezafibrate) led to a decrease in oxygen affinity and increase in cooperative energy. Kinetic studies at pH 7.0 and 20 degrees C revealed that (i), the overall rate of oxygen dissociation is 1.4-fold slower than that for HbA and (ii), the carbon monoxide dissociation rate is unaffected. The abnormal properties of this hemoglobin variant can be attributed to a more 'relaxed' T-state.