Resonance Raman Spectra of Photodissociated Hemoglobins: Implications on Cooperative Mechanisms

D. L. Rousseau, M. R. Ondrias

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

Resonance Raman spectra at cryogenic temperatures of photodissociated hemoglobins and the corresponding deoxygenated preparations are compared and significant differences are found in modes with contributions from peripheral substituents of the heme as well as in the iron-histidine stretching mode. These differences in heme vibrational spectra reflect differences in the tertiary structure of the heme pocket between deoxyhemoglobin and the CO-bound form. An analysis of the effects of cooperative energy storage on the tertiary structure around the heme is made and used to interpret this resonance Raman data. The differences between the spectra of the deoxygenated preparations and the photoproducts provide evidence that a fraction of the free energy of cooperativity, ΔG, is located away from the heme. These data support models for cooperativity in which the cooperative energy is distributed over many bonds or is localized in protein bonds only, such as those at the subunit interface. In addition, the local changes in amino acid positions, which must occur following the change in the state of ligand binding, may drive the changes in the structural relationships of the subunits and hence form one of the initial steps for triggering the quaternary structure transition.

Original languageEnglish (US)
Pages (from-to)537-545
Number of pages9
JournalBiophysical journal
Volume47
Issue number4
DOIs
StatePublished - Jan 1 1985
Externally publishedYes

ASJC Scopus subject areas

  • Biophysics

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