A conformational switch to β-sheet structure in cytochrome c leads to heme exposure. Implications for cardiolipin peroxidation and apoptosis

Gurusamy Balakrishnan, Ying Hu, Oyeyemi F. Oyerinde, Jia Su, John Taylor Groves, Thomas G. Spiro

Research output: Contribution to journalArticle

57 Scopus citations

Abstract

Ultraviolet resonance Raman spectroscopy reveals that, when heated at pH 3, a substantial fraction (30%) of cytochrome c converts to a β-sheet structure, at the expense of turns and helices. β-sheet formation is rapid, exhibiting a 2 μs rise time, following a temperature jump. It is proposed that a short β-sheet segment, comprising residues 37-39 and 58-61, extends itself into the large 37-61 loop when the latter is destabilized by protonation of H26, which forms an anchoring H-bond to loop residue P44. This conformation change ruptures the Met80-Fe bond, as revealed by changes in ligation-sensitive heme-resonant Raman bands. It also induces peroxidase activity with the same temperature profile. This process is suggested to model the apoptotic peroxidation of cardiolipin by cytochrome c.

Original languageEnglish (US)
Pages (from-to)504-505
Number of pages2
JournalJournal of the American Chemical Society
Volume129
Issue number3
DOIs
StatePublished - Jan 24 2007

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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