title: Selective oxidation of methionine beta(55)D6 at the alpha 1 beta 1 interface in hemoglobin completely destabilizes the T-state.
abstract: When methionine beta(55)D6 in human hemoglobin is oxidized to its sulfoxide derivative, the modified protein appears to maintain most of the chemical and structural properties typical of the native protein. On the contrary, the functional behavior is drastically changed, being characterized (like that of the isolated chains) by high oxygen affinity (p50 = 0.47 torr in 0.1 M Tris (pH 7.3) + 0.1 M NaCl at 25 degrees C), absence of cooperativity (n = 1), and lack of Bohr effect. The complete destabilization of the T-state as a result of this modification is related to a perturbation of the alpha 1 beta 1 subunit interface, which in native hemoglobin remains static during the quaternary ligand-linked transition. Results also suggest that methionyl sulfoxide-containing hemoglobin, obtained under different conditions, assumes functionally different R-states, none of which is exactly comparable with that typical of the native protein.
authors: Department of Biochemical Sciences, University La Sapienza, Rome, Italy.
authors: G
authors: G
authors: Amiconi
authors: F
authors: F
authors: Ascoli
authors: D
authors: D
authors: Barra
authors: A
authors: A
authors: Bertollini
authors: R M
authors: RM
authors: Matarese
authors: D
authors: D
authors: Verzili
authors: M
authors: M
authors: Brunori
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002162:Camelus; D002700:Chloramines / Q000494:pharmacology; D006441:Hemoglobin A / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D046911:Macromolecular Substances; D008715:Methionine; D009211:Myoglobin / Q000378:metabolism; D010084:Oxidation-Reduction; D010108:Oxyhemoglobins / Q000378:metabolism; D010449:Peptide Mapping; D013045:Species Specificity; D014105:Tosyl Compounds; D014357:Trypsin
chemical_list: D000596:Amino Acids; D002700:Chloramines; D046911:Macromolecular Substances; D009211:Myoglobin; D010108:Oxyhemoglobins; D014105:Tosyl Compounds; C016300:chloramine-T; D006441:Hemoglobin A; D008715:Methionine; D014357:Trypsin