Peroxynitrite detoxification by horse heart carboxymethylated cytochrome c is allosterically modulated by cardiolipin

Paolo Ascenzi, Chiara Ciaccio, Federica Sinibaldi, Roberto Santucci, Massimo Coletta

Research output: Contribution to journalArticlepeer-review

Abstract

Carboxymethylation of equine heart cytochrome c (cytc) changes its tertiary structure by disrupting the heme-Fe-Met80 distal bond, such that carboxymethylated cytc (CM-cytc) displays myoglobin-like properties. Here, the effect of cardiolipin (CL) on peroxynitrite isomerization by ferric CM-cytc (CM-cytc-Fe(III)) is reported. Unlike native ferric cytc (cytc-Fe(III)), CM-cytc-Fe(III) catalyzes peroxynitrite isomerization, the value of the second order rate constant (k on) is 6.8×10 4M -1s -1. However, CM-cytc-Fe(III) is less effective in peroxynitrite isomerization than CL-bound cytc-Fe(III) (CL-cytc-Fe(III); k on=3.2×10 5M -1s -1). Moreover, CL binding to CM-cytc-Fe(III) facilitates peroxynitrite isomerization (k on=5.3×10 5M -1s -1). Furthermore, the value of the dissociation equilibrium constant for CL binding to CM-cytc-Fe(III) (K=1.8×10 -5M) is lower than that reported for CL-cytc-Fe(III) complex formation (K=5.1×10 -5M). Although CM-cytc-Fe(III) and CL-cytc-Fe(III) display a different heme distal geometry and heme-Fe(III) reactivity, the heme pocket and the CL cleft are allosterically linked.

Original languageEnglish
Pages (from-to)463-467
Number of pages5
JournalBiochemical and Biophysical Research Communications
Volume415
Issue number3
DOIs
Publication statusPublished - Nov 25 2011

Keywords

  • Allostery
  • Carboxymethylated cytochrome c
  • Cardiolipin-bound carboxymethylated cytochrome c
  • Horse heart cytochrome c
  • Kinetics
  • Peroxynitrite isomerization

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Cell Biology
  • Molecular Biology

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