title: Elongation of the Fe-His bond in the α subunit induced by binding of the allosteric effector bezafibrate to hemoglobins.
abstract: Human adult hemoglobin (HbA), possessing an α(2)β(2) tetramer structure, efficiently transports oxygen from the lungs to the tissues. The oxygen affinity of HbA has been shown to be regulated by organic phosphates such as 2,3-bisphosphoglycerate (BPG). Bezafibrate (BZF) is also known to alter the oxygen affinity of HbA through a mechanism largely different from that of BPG. The interaction of HbA with BZF has been characterized by (1)H NMR to elucidate the molecular mechanism responsible for the functional alteration of HbA. Paramagnetically shifted heme methyl proton signals of only the α subunit of met-azido HbA exhibited sizable downfield shifts in the presence of BZF. Since met-azido HbA exhibits the so-called thermal spin equilibrium between high and low spin states, the BZF-induced shift changes observed for the α signals can be attributed to an increase in the high spin contents in the subunit, possibly due to the elongation of the Fe-His bond.
authors.affiliation: Department of Chemistry, University of Tsukuba, Tsukuba, Ibaraki, Japan. nagatomo@chem.tsukuba.ac.jp
authors.forename: Shigenori
authors.initials: S
authors.lastname: Nagatomo
authors.forename: Hiromi
authors.initials: H
authors.lastname: Hamada
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yoshikawa
mesh_terms: D000328:Adult; D000494:Allosteric Regulation / Q000187:drug effects; D001629:Bezafibrate / Q000494:pharmacology*; D005319:Fetal Hemoglobin / Q000737:chemistry / Q000378:metabolism; D006441:Hemoglobin A / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism
chemical_list: D021122:Protein Subunits; D006441:Hemoglobin A; D005319:Fetal Hemoglobin; D001629:Bezafibrate