Subunit Dissociation of the Abnormal Hemoglobins G Georgia (α2Leu (G2) β2) and Rampa (α2Ser (G2) β2)
1972; Elsevier BV; Volume: 247; Issue: 5 Linguagem: Inglês
10.1016/s0021-9258(19)45576-2
ISSN1083-351X
AutoresLinda L. Smith, C.F. Plese, Betty P. Barton, Samuel Charache, Jerry B. Wilson, Titus H.J. Huisman,
Tópico(s)Neonatal Health and Biochemistry
ResumoAbstract The liganded derivatives of hemoglobins G Georgia (α295Leu (G2) β2) and Rampa (α295Ser (G2) β2) were found by sedimentation velocity, viscosity, and diffusion measurements to be extensively dissociated into dimers in 0.1 m NaCl at pH 7.2 to 7.4 and 25°. The deoxygenated derivatives of both hemoglobin variants are tetramers under the same conditions. The deoxyhemoglobins also retain a predominantly tetrameric structure in NaCl solutions of increasing concentration up to 2 m, and in dilute alkaline buffers, at least to pH 9.8. In addition, association-dissociation in oxy- or cyanferrihemoglobin Rampa is both pH- and temperature-dependent. The liganded Rampa molecule is primarily a tetramer at 4° in the pH range 6 to 7, whereas liganded hemoglobin G Georgia shows only slightly increased tetramer formation under identical conditions. Both hemoglobin G Georgia and hemoglobin Rampa have decreased heme-heme interactions and increased oxygen affinities.
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