Absence of cooperative energy at the heme in liganded hemoglobins

Denis L. Rousseau, S. L. Tan, M. R. Ondrias, S. Ogawa, R. W. Noble

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Using resonance Raman and infrared absorption spectroscopies, we show that there are no energetically significant structural changes at the heme upon the quaternary structure transition in six-coordinate hemoglobins. These observations are at variance with the presently accepted mechanism for cooperativity, which postulates severe strain in the T quaternary structure of liganded hemoglobin. By consideration of the present results, and studies on deoxyhemoglobins and photodissociated hemoglobins, a view of the distribution of the free energy of cooperativity emerges. In five-coordinate deoxyhemoglobins the iron-histidine bond is able to respond to the protein structure, thereby accounting for a wide variation (40 cm-1) in its frequency. In contrast, when a sixth ligand is present and the iron is pulled into plane, the histidine-heme-ligand complex becomes structurally rigid, thereby preventing protein-induced changes at the heme. Instead, in liganded hemoglobin the changes in structure that occur at the subunit interface upon the quaternary structure transition are accommodated away from the heme by relatively weak bonds in the protein.

Original languageEnglish (US)
Pages (from-to)2857-2865
Number of pages9
JournalBiochemistry
Volume23
Issue number13
StatePublished - 1984
Externally publishedYes

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Heme
Hemoglobins
Histidine
Iron
Ligands
Proteins
Infrared absorption
Absorption spectroscopy
Free energy
Infrared spectroscopy
Spectrum Analysis
deoxyhemoglobin

ASJC Scopus subject areas

  • Biochemistry

Cite this

Rousseau, D. L., Tan, S. L., Ondrias, M. R., Ogawa, S., & Noble, R. W. (1984). Absence of cooperative energy at the heme in liganded hemoglobins. Biochemistry, 23(13), 2857-2865.

Absence of cooperative energy at the heme in liganded hemoglobins. / Rousseau, Denis L.; Tan, S. L.; Ondrias, M. R.; Ogawa, S.; Noble, R. W.

In: Biochemistry, Vol. 23, No. 13, 1984, p. 2857-2865.

Research output: Contribution to journalArticle

Rousseau, DL, Tan, SL, Ondrias, MR, Ogawa, S & Noble, RW 1984, 'Absence of cooperative energy at the heme in liganded hemoglobins', Biochemistry, vol. 23, no. 13, pp. 2857-2865.
Rousseau DL, Tan SL, Ondrias MR, Ogawa S, Noble RW. Absence of cooperative energy at the heme in liganded hemoglobins. Biochemistry. 1984;23(13):2857-2865.
Rousseau, Denis L. ; Tan, S. L. ; Ondrias, M. R. ; Ogawa, S. ; Noble, R. W. / Absence of cooperative energy at the heme in liganded hemoglobins. In: Biochemistry. 1984 ; Vol. 23, No. 13. pp. 2857-2865.
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