Nuclear magnetic resonance studies of equilibrated and reconstituted forms of hemoglobin
High resolution proton nuclear magnetic resonance (/sup 1/H NMR) spectroscopy is used to investigate the structure-function relationships and dynamic properties of human adult hemoglobin (Hb A). Several resonances arising from the heme and the bound ligand are located and assigned. The /sup 1/H NMR spectra of ferric low spin complexes of Hb A and its ..cap alpha.. and ..beta.. subunits are studied in detail. Differences in the position of hyperfine shifted resonances of the subunits comprising the isolated and tetrameric Hb forms of the met-azido complex reflect alteration of the spin state. This change in the spin state stems from axial perturbation of the hemes of specific subunits. /sup 1/H NMR study of the reaction of apo-Hb with heme reveals that the holoprotein is initially formed as a mixture of slowly interconverting isomers; each subunit possesses two possible orientations differing by a 180/sup 0/ rotation about the ..cap alpha..-..gamma.. meso axis, only one corresponding to the native heme orientation. The reaction rates for the equilibration of the heme reorientation reaction differ dramatically for met-aquo and met-azido derivatives. As a result of experiments involving isotope labeled hemins and kinetic control of the rotational disorder in Hb, resonances arising from the reversed heme are unambiguously assigned.
- Research Organization:
- California Univ., Davis (USA)
- OSTI ID:
- 6407560
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
62 RADIOLOGY AND NUCLEAR MEDICINE
ADULTS
AGE GROUPS
ANIMALS
BARYONS
BIOCHEMICAL REACTION KINETICS
CARBOXYLIC ACIDS
ELEMENTARY PARTICLES
FERMIONS
GLOBIN
HADRONS
HEMOGLOBIN
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
KINETICS
MAGNETIC RESONANCE
MAMMALS
MAN
MOLECULAR STRUCTURE
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEONS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PIGMENTS
PORPHYRINS
PRIMATES
PROTEINS
PROTONS
REACTION KINETICS
RESONANCE
SPECTRA
VERTEBRATES