Evidence for proximal control of ligand specificity in hemeproteins: Absorption and Raman studies of cryogenically trapped photoproducts of ligand bound myoglobins

A. M. Ahmed, B. F. Campbell, D. Caruso, M. R. Chance, M. D. Chavez, S. H. Courtney, Joel M. Friedman, I. E T Iben, M. R. Ondrias, M. Yang

Research output: Contribution to journalArticle

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Abstract

The absorption and resonance Raman spectra of cryogenically trapped photoproducts of oxy and carboxy derivatives of myoglobin (Mb) are compared and analyzed in an attempt to understand the structural basis for ligand specificity in hemeproteins. Pulsed and cw excitations over a wide temperature range are used in order to differentiate between kinetic hole burning (KHB), optical pumping of structural relaxation, and spontaneous relaxation effects. Using these techniques, we are able to correlate changes in the absorption spectrum (band III at ≈ 760 nm) with low-frequency Raman bands. Based on these correlations we are able to determine which proximal heme pocket parameters are participating in KHB and optical pumping phenomena. Differences in the spectra of the ligand specific photoproducts have revealed differences in the populations of conformational substates (CS) that participate in the geminate recombination (process I) at cryogenic temperatures. A model is presented that relates the ligand specific spectral differences to structural and functional differences in the bound protein. What emerges is evidence that Mb and hemoglobin (Hb) can differentiate between O2 and CO based on proximal control of the bond forming step between the ligand and the iron.

Original languageEnglish (US)
Pages (from-to)329-351
Number of pages23
JournalChemical Physics
Volume158
Issue number2-3
DOIs
StatePublished - Dec 15 1991
Externally publishedYes

Fingerprint

Hemeproteins
myoglobin
Myoglobin
Ligands
Optical pumping
ligands
hole burning
optical pumping
Structural relaxation
Kinetics
kinetics
hemoglobin
Carbon Monoxide
cryogenic temperature
Heme
Cryogenics
Raman scattering
Absorption spectra
Hemoglobins
Iron

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Spectroscopy
  • Atomic and Molecular Physics, and Optics

Cite this

Evidence for proximal control of ligand specificity in hemeproteins : Absorption and Raman studies of cryogenically trapped photoproducts of ligand bound myoglobins. / Ahmed, A. M.; Campbell, B. F.; Caruso, D.; Chance, M. R.; Chavez, M. D.; Courtney, S. H.; Friedman, Joel M.; Iben, I. E T; Ondrias, M. R.; Yang, M.

In: Chemical Physics, Vol. 158, No. 2-3, 15.12.1991, p. 329-351.

Research output: Contribution to journalArticle

Ahmed, A. M. ; Campbell, B. F. ; Caruso, D. ; Chance, M. R. ; Chavez, M. D. ; Courtney, S. H. ; Friedman, Joel M. ; Iben, I. E T ; Ondrias, M. R. ; Yang, M. / Evidence for proximal control of ligand specificity in hemeproteins : Absorption and Raman studies of cryogenically trapped photoproducts of ligand bound myoglobins. In: Chemical Physics. 1991 ; Vol. 158, No. 2-3. pp. 329-351.
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