Structural nonequivalence of the α- and β- heme-pockets in human methemoglobin. A proton magnetic relaxation study in solution

B. Markovska, G. D. Efremov, S. Vuk-Pavlović, B. Benko, S. Maričić

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

Solvent-proton longitudinal magnetic relaxation rates as dependent on temperature were measured for human (H)/canine (C) valency hybrids of the type {αH(III)βC(II)}2 and {αC(II)βH(III)}2. The two metheme irons in the human methemoglobin chains induce quite different proton magnetic relaxation (pmr) rates reflecting a tighter β-heme-pocket compared to the α subunit. Both heme-pockets appear to be loosened in the presence of inositol hexaphosphate (IHP) although this allosteric effector binds only to the β chains, the binding assumed to be the same for canine as for human hemoglobin. The subunit nonequivalence is retained also in the T-quaternary state induced by IHP. In the species hybrids the pmr rates due to the metheme iron are sensitive to the valency (ligand) state, which was either CO or H2O in the partner half of the hybrid. All results show very clearly the interrelationship of the tertiary (protomer) structure with the quaternary (oligomer) structure in hemoglobin.

Original languageEnglish (US)
Pages (from-to)337-342
Number of pages6
JournalArchives of Biochemistry and Biophysics
Volume171
Issue number1
DOIs
StatePublished - Nov 1975

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology

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