Vibrational structure of the formyl group on heme a. Implications on the properties of cytochrome c oxidase

S. W. Han, Y. C. Ching, S. L. Hammes, D. L. Rousseau

Research output: Contribution to journalArticle

21 Scopus citations

Abstract

Resonance Raman spectra have been recorded for heme a derivatives in which the oxygen atom of the formyl group has been isotopically labeled and for Schiff base derivatives of heme a in which the Schiff base nitrogen has been isotopically labeled. The 14N-15N isotope shift in the C = N stretching mode of the Schiff base is close to the theoretically predicted shift for an isolated C = N group for both the ferric and ferrous oxidation states and in both aqueous and nonaqueous solutions. In contrast, the 16O-18O isotope shift of the C = O stretching mode of the formyl group is significantly smaller than that predicted for an isolated C = O group and is also dependent on whether the environment is aqueous or nonaqueous. This differences between the theoretically predicted shifts and the observed shifts are attributed to coupling of the C = O stretching mode to as yet unidentified modes of the heme. The complex behavior of the C = O stretching vibration precludes the possibility of making simple interpretations of frequency shifts of this mode in cytochrome c oxidase.

Original languageEnglish (US)
Pages (from-to)45-52
Number of pages8
JournalBiophysical journal
Volume60
Issue number1
DOIs
StatePublished - Jan 1 1991
Externally publishedYes

ASJC Scopus subject areas

  • Biophysics

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