Magnetic circular dichroism on oxygen complexes of hemoproteins Correlation between magnetic circular dichroism magnitude and electronic structures of oxygen complexes

Tunenori Nozawa, Nagao Kobayashi, Masahiro Hatano, Motoji Ueda, Masaru Sogami

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)

Abstract

Magnetic circular dichroism (MCD) and natural circular dichroism (CD) spectra are reported for horseradish peroxidase Compounds II and III, and kangaroo myoglobin Compound II at pH values of 8.5 and 4.9. These compounds exhibited MCD spectra of apparent Faraday A term both in the Soret and Q regions, except for myoglobin compounds in the Soret region where intrinsic temperature dependence showed large contribution from Faraday C terms. Comparison of these data with the MCD spectra of the dioxygen complexes of hemoglobin (myoglobin) and cytochrome P-450 revealed that the magnitude of the apparent Faraday A term trough at the Q0-0 bands decreased in the order of O2 complexes of hemoglobin (myoglobin) ([θ]M ≒ 16) > horseradish peroxidase Compound III ([θ]M ≒ 8) > O2 complex of cytochrome P-450 ([θ]M ≒ 4). The [θ]M values of the oxygen complex of cytochrome P-450 is similar to those observed for the compounds II of horseradish peroxidase and kangaroo myoglobin. From these observations it was concluded that the magnitude of MCD, especially the trough depth of the Q0-0 band, has direct correlation to the electronic states of the oxygen complexes of the hemoproteins. The implication of the findings was discussed in terms of the iron electronic structures perturbed by the axial ligation.

Original languageEnglish
Pages (from-to)282-290
Number of pages9
JournalBBA - Protein Structure
Volume626
Issue number2
DOIs
Publication statusPublished - 1980 Dec 16

Keywords

  • (Horse radish, Kangaroo)
  • Compound H
  • Hemoprotein
  • Myoglobin
  • Oxygen complex
  • Peroxidase

ASJC Scopus subject areas

  • Medicine(all)

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