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The pathway of allosteric control as revealed by hemoglobin intermediate states
Author(s) -
Holt Jo M.,
Ackers Gary K.
Publication year - 1995
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.9.2.7781923
Subject(s) - tetramer , allosteric regulation , protein quaternary structure , chemistry , cooperativity , hemoglobin , stereochemistry , crystallography , bohr effect , allosteric enzyme , biophysics , biochemistry , receptor , protein subunit , biology , enzyme , oxygen–haemoglobin dissociation curve , gene
The energetics of hemoglobin cooperativity has been analyzed through the use of stable, partially‐ligated intermediates. These studies revealed that the two dimeric halves of the tetramer are autonomous, leading to a Symmetry Rule that governs the relationship between ligand‐binding and the T å R quaternary switch: the R structure is favored over T only when ligands are bound to both dimers within the tetramer. A major feature of the Symmetry Rule mechanism is the generation of cooperative free energy by tertiary conformational constraints, which are formed within one dimeric half of the T‐tetramer and released during the quaternary structure change to R. These rules of tertiary and quaternary molecular switching also govern the roles of the heterotropic allosteric effectors (e.g. Bohr protons).—Holt, J. M., Ackers, G. K. The pathway of allosteric control as revealed by hemoglobin intermediate states. FASEB J. 9, 210–218 (1995)