EPR studies on the photoinduced intermediates of NO complexes in recombinant ferric-Mb trapped at low temperatures

Hiroshi Hori, Futoshi Masuya, Yi Dou, Masao Ikeda-Saito

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

The nitrosyl complex of ferric myoglobin is EPR-silent. Upon photolysis at low temperatures, the photoinduced intermediates trapped in the distal heme cavity exhibit new EPR spectra due to the interaction between the photodissociated NO (S=1/2) and the ferric high spin heme (S=5/2). In order to elucidate the effect of distal E7 (His64) and E11 (Val68) mutations upon the electronic structure of the metal center, its immediate environment, and its interaction with the photodissociated NO, EPR spectra of the photoproducts of the NO complexes of recombinant ferric Mb mutants were measured at 5 K. EPR spectra of the photoproducts were closely related to the size and/or the polarity of the distal pocket residues. The distal pocket of the E7 mutants seemed to be sterically crowded, even decreasing the side chain volume or changing its hydrophobicity by replacing amino acid at position 64. We have found that the mobility of the photodissociated NO molecule in the distal heme pocket was strongly governed by the nature of the amino acid residue at E11 position. Copyright (C) 2000 Elsevier Science B.V.

Original languageEnglish
Pages (from-to)181-187
Number of pages7
JournalJournal of Inorganic Biochemistry
Volume82
Issue number1-4
DOIs
Publication statusPublished - 2000

Keywords

  • Distal heme pocket
  • EPR
  • Ferric-Mb mutants
  • NO
  • Photolysis

ASJC Scopus subject areas

  • Biochemistry
  • Inorganic Chemistry

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