Quaternary transformation induced changes at the heme in deoxyhemoglobins
- 1 July 1982
- journal article
- research article
- Published by American Chemical Society (ACS) in Biochemistry
- Vol. 21 (14) , 3428-3437
- https://doi.org/10.1021/bi00257a028
Abstract
Quaternary-structure-induced differences in the high- and low-frequency regions of the resonance Raman spectrum of the heme were detected in a variety of Hb. These differences may be the result of changes in the amino acid sequence, induced by genetic and chemical modifications, and alterations in the quaternary structure. For samples in solution in low ionic strength buffers, differences in the 1357-cm-1 line (an electron-density-sensitive vibrational mode) correlated with differences in the 216-cm-1 line (the Fe-histidine stretching mode). Changes in the Fe-histidine bond and changes in the .pi.-electron density of the porphyrin depended upon a common heme-globin interaction. The quaternary-structure-induced changes in the vibrational modes associated with the heme demonstrated that there was extensive communication between the heme and the globin and impact on models for the energetics of cooperativity. The local interactions of the Fe-histidine mode were energetically small and destabilized the deoxy heme in the T structure with respect to the R structure. These interactions must be larger in the ligated protein than in the deoxy protein to obtain a negative free energy of cooperativity. The deprotonation of the proximal histidine does not play a major role in the energetics of cooperativity. Models for cooperativity that require conformational changes in the Fe-histidine bond or direct interaction between the porphyrin and the protein were qualitatively consistent with the observed variation of heme electronic structure in concert with protein quaternary structure.This publication has 18 references indexed in Scilit:
- Porphyrins. 39. Ammine and nitridoosmium porphyrins. Ligand effects on the electronic structure of osmium octaethylporphyrinsJournal of the American Chemical Society, 1980
- Resonance Raman examination of axial ligand bonding and spin-state equilibriums in metmyoglobin hydroxide and other heme derivativesBiochemistry, 1979
- Protein-heme interaction in hemoglobin: evidence from Raman difference spectroscopy.Proceedings of the National Academy of Sciences, 1979
- Protein influence on the heme in cytochrome c: evidence from Raman difference spectroscopy.Proceedings of the National Academy of Sciences, 1979
- Porphyrin core expansion and doming in heme proteins. New evidence from resonance Raman spectra of six-coordinate high-spin iron(III) hemesJournal of the American Chemical Society, 1979
- Haemoglobin: The structural changes related to ligand binding and its allosteric mechanismJournal of Molecular Biology, 1979
- Coupling between oxidation state and hydrogen bond conformation in heme proteinsProceedings of the National Academy of Sciences, 1979
- Resonance Raman and electron paramagnetic resonance studies of the quaternary structure change in carp hemoglobin. Sensitivity of these spectroscopic probes to heme strainJournal of the American Chemical Society, 1979
- Absence of heme-localized strain in T state hemoglobin: insensitivity of heme-imidazole resonance Raman frequencies to quaternary structure.Proceedings of the National Academy of Sciences, 1979
- Protein control of porphyrin conformation. Comparison of resonance Raman spectra of heme proteins with mesoporphyrin IX analogsJournal of the American Chemical Society, 1976