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Mutual effects of proton and sodium chloride on oxygenation of liganded human hemoglobin
Author(s) -
Lepeshkevich Sergei V.,
Dzhagarov Boris M.
Publication year - 2005
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2005.05008.x
Subject(s) - tetramer , chemistry , bohr effect , hemoglobin , dimer , flash photolysis , dissociation (chemistry) , protein subunit , reaction rate constant , dissociation constant , kinetics , hemeprotein , crystallography , stereochemistry , biophysics , heme , biochemistry , oxygen–haemoglobin dissociation curve , organic chemistry , receptor , enzyme , biology , gene , physics , quantum mechanics
The different effects of pH and NaCl on individual O 2 ‐binding properties of α and β subunits within liganded tetramer and dimer of human hemoglobin (HbA) were examined in a number of laser time‐resolved spectroscopic measurements. A previously proposed approach [Dzhagarov BM & Lepeshkevich SV (2004) Chem Phys Lett 390 , 59–64] was used to determine the extent of subunit dissociation rate constant difference and subunit affinity difference from a single flash photolysis experiment. To investigate the effect of NaCl concentration on the association and dissociation rate constants we carried out a series of experiments at four different concentrations (0.1, 0.5, 1.0 and 2.0 m NaCl) over the pH range of the alkaline Bohr effect. As the data suggest, the individual properties of the α and β subunits within the completely liganded tetrameric hemoglobin did not depend on pH under salt‐free conditions. However, different effects NaCl on the individual kinetic properties of the α and β subunits were revealed. Regulation of the O 2 ‐binding properties of the α and β subunits within the liganded tetramer is proposed to be attained in two quite different ways.