Selective oxidation of methionine beta(55)D6 at the alpha 1 beta 1 interface in hemoglobin completely destabilizes the T-state

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 th...

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Bibliographic Details
Published inThe Journal of biological chemistry Vol. 264; no. 30; p. 17745
Main Authors Amiconi, G, Ascoli, F, Barra, D, Bertollini, A, Matarese, R M, Verzili, D, Brunori, M
Format Journal Article
LanguageEnglish
Published United States American Society for Biochemistry and Molecular Biology 25.10.1989
Subjects
Amino Acids - analysis
Animals
Camelus
Chloramines - pharmacology
Hemoglobin A - metabolism
Humans
Kinetics
Macromolecular Substances
Methionine
Myoglobin - metabolism
Oxidation-Reduction
Oxyhemoglobins - metabolism
Peptide Mapping
Species Specificity
Tosyl Compounds
Trypsin
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Summary: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.
ISSN:0021-9258
1083-351X