Linkage of Functional and Structural Heterogeneity in Proteins: Dynamic Hole Burning in Carboxymyoglobin

Inhomogeneous broadening of the 760-nanometer photoproduct band of carboxymyoglobin at cryogenic temperatures has been demonstrated with a dynamic hole burning technique. Line-shape changes and frequency shifts in this spectral band are generated by ligand recombination and are shown not to be the r...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 1987-10, Vol.238 (4825), p.373-376
Main Authors: Campbell, Blair F., Chance, Mark R., Friedman, Joel M.
Format: Article
Language:English
Subjects:
Absorption spectra
Animals
Biochemistry
Biological and medical sciences
Carbon Monoxide - metabolism
Cryogenic temperature
Fundamental and applied biological sciences. Psychology
Infrared spectroscopy
Interactions. Associations
Intermolecular phenomena
Kinetics
Ligands
Line spectra
Methods
Molecular biophysics
Muscular disorders
Myoglobin
Myoglobin - metabolism
Photochemistry
Protein Binding
Protein Conformation
Protein research
Proteins
Signal reflection
Spectral bands
Spectrophotometry
Spectrophotometry, Infrared
Temperature
Visible spectrum
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Summary:Inhomogeneous broadening of the 760-nanometer photoproduct band of carboxymyoglobin at cryogenic temperatures has been demonstrated with a dynamic hole burning technique. Line-shape changes and frequency shifts in this spectral band are generated by ligand recombination and are shown not to be the result of structural relaxation below 60 K. The observation of dynamic hole burning exposes the relation between the structural disorder responsible for the inhomogeneous broadening and the well-known distributed ligand rebinding kinetics. The findings provide direct evidence for the functional relevance of conformational substates in myoglobin rebinding. In addition, a general protocol for evaluating the relative contributions of structural relaxation and hole burning to the spectral changes accompanying ligand rebinding in hemeproteins is presented.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.3659921