Conformational changes in the hemoglobin S system as seen by proton binding.

H P Scholberg; C Fronticelli; E Bucci

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PubMed · 7410379

Conformational changes in the hemoglobin S system as seen by proton binding.

H P Scholberg·C Fronticelli·E Bucci

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Abstract

The proton binding behavior of the carbon monoxy derivatives of hemoglobins A and S, the respective beta-subunits (in the native form and with the cysteines combined with p-mercuribenzoate), and the respective beta (1-55) peptides have been measured. The results show that in the systems obtained from hemoglobin S there is a group which shifts its pK from about 7.0 to 8.35 in the beta-subunits that were reacted with p-mercuribenzoate and to more than 9.0 in the beta (1-55) peptide. Proton nuclear magnetic resonance measurements indicate that in the peptide beta (1-55) from hemoglobin S this residue is the histidine at beta 2. It is proposed that this pK shift is due to the formation of a salt bridge between beta 2 His and beta 7 Glu. This structure would disrupt the first turn of the A helix of the beta s-subunits. Its stabilization by extramolecular contacts may be relevant to the mechanism of fiber formation of hemoglobin S.

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Carboxyhemoglobin Heme Hemoglobin A Hemoglobin, Sickle Histidine Humans Hydrogen-Ion Concentration Macromolecular Substances Magnetic Resonance Spectroscopy Mercuribenzoates Osmolar Concentration Protein Binding Protein Conformation Comparative Study Journal Article Research Support, U.S. Gov't, P.H.S.

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H P Scholberg, C Fronticelli, E Bucci. 1980-09-25. Conformational changes in the hemoglobin S system as seen by proton binding.. https://pubmed.ncbi.nlm.nih.gov/7410379/

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