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Oxidative modification of methionine80 in cytochrome c by reaction with peroxides

Ari Dwi Nugraheni1, Chunguang Ren1, Yorifumi Matsumoto1

  • 1Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan.

Journal of Inorganic Biochemistry
|March 7, 2018
PubMed

Insights

Cardiolipin interaction with cytochrome c (cyt c) cleaves the Met80-heme bond, enhancing peroxidase activity and promoting apoptosis. This study shows selective Met80 oxidation by mCPBA in cardiolipin-containing liposomes, forming a potent ferryl species.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Background:

  • Cytochrome c (cyt c) plays a crucial role in apoptosis and mitochondrial function.
  • The Met80-heme iron bond in cyt c is known to be cleaved by cardiolipin (CL) interaction.
  • This dissociation enhances cyt c's peroxidase activity and facilitates its release during apoptosis.

Purpose of the Study:

  • To demonstrate the selective oxidation of Met80 in cyt c by meta-chloroperbenzoic acid (mCPBA).
  • To investigate the formation of a ferryl species (Compound I) in the presence of CL-containing liposomes.
  • To characterize the impact of Met80 modification on cyt c's peroxidase activity.

Main Methods:

  • Reaction of ferric cyt c with mCPBA in the presence of 1,2-dioloeyl-sn-glycero-3-phosphocholine (DOPC) liposomes with and without CL.
  • Peptide fragment analysis using electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (MS/MS).
  • Spectroscopic analysis (transient absorption) to detect the formation of reactive intermediates.

Main Results:

  • A specific peptide fragment (m/z = 795.45) with a 16 Da mass increase at Met80 was detected only in reactions with CL-containing liposomes.
  • Purified Met80-modified cyt c showed over a 5-fold increase in peroxidase activity compared to unmodified cyt c.
  • Transient absorption bands at 650 nm indicated the formation of Compound I, with formation and decomposition rates dependent on mCPBA concentration.

Conclusions:

  • CL facilitates the selective oxidation of Met80 in cyt c by mCPBA, leading to enhanced peroxidase activity.
  • The formation of a ferryl species (Compound I) is implicated in this enhanced activity.
  • This Met80 modification mechanism may contribute to the pro-apoptotic functions of cyt c.
Keywords:
Cytochrome cMethionine oxidationPeroxidase reactionSelf-modification

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