Quaternary structure of hemoglobin in solution
AUTOR(ES)
Lukin, Jonathan A.
FONTE
The National Academy of Sciences
RESUMO
Many important proteins perform their physiological functions under allosteric control, whereby the binding of a ligand at a specific site influences the binding affinity at a different site. Allosteric regulation usually involves a switch in protein conformation upon ligand binding. The energies of the corresponding structures are comparable, and, therefore, the possibility that a structure determined by x-ray diffraction in the crystalline state is influenced by its intermolecular contacts, and thus differs from the solution structure, cannot be excluded. Here, we demonstrate that the quaternary structure of tetrameric human normal adult carbonmonoxy-hemoglobin can readily be determined in solution at near-physiological conditions of pH, ionic strength, and temperature by NMR measurement of 15N-1H residual dipolar couplings in weakly oriented samples. The structure is found to be a dynamic intermediate between two previously solved crystal structures, known as the R and R2 states. Exchange broadening at the subunit interface points to a rapid equilibrium between different structures that presumably include the crystallographically observed states.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=141027Documentos Relacionados
- Rate of quaternary structure change in hemoglobin measured by modulated excitation.
- Quaternary structure dynamics and carbon monoxide binding kinetics of hemoglobin valency hybrids.
- Bracelet protein: a quaternary structure proposed for the giant extracellular hemoglobin of Lumbricus terrestris.
- Quaternary enhancement in binding of oxygen by human hemoglobin
- Absence of heme-localized strain in T state hemoglobin: insensitivity of heme-imidazole resonance Raman frequencies to quaternary structure.