Effect of varying polyglutamate chain length on the structure and stability of ferricytochrome c

Marián Antalík, Jaroslava Bágel'ová, Zuzana Gažová, Andrej Musatov, Diana Fedunová

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15 Scopus citations


The effect of varying polyglutamate chain length on local and global stability of horse heart ferricytochrome c was studied using scanning calorimetry and spectroscopy methods. Spectral data indicate that polyglutamate chain lengths equal or greater than eight monomer units significantly change the apparent pKa for the alkaline transition of cytochrome c. The change in pKa is comparable to the value when cytochrome c is complexed with cytochrome bc1. Glutamate and diglutamate do not significantly alter the temperature transition for cleavage of the Met 80-heme iron bond of cytochrome c. At low ionic strength, polyglutamates consisting of eight or more glutamate monomers increase midpoint of the temperature transition from 57.3±0.2 to 66.9±0.2°C. On the other hand, the denaturation temperature of cytochrome c decreases from 85.2±0.2 to 68.8±0.2°C in the presence of polyglutamates with number of glutamate monomers n≳8. The rate constant for cyanide binding to the heme iron of cytochrome c of cytochrome c-polyglutamate complex also decreases by ∼42.5% with n≳8. The binding constant for the binding of octaglutamate (m.w.∼1000) to cyt c was found to be 1.15×10 5 M-1 at pH 8.0 and low ionic strength. The results indicate that the polyglutamate (n≳8) is able to increase the stability of the methionine sulfur-heme iron bond of cytochrome c in spite of structural differences that weaken the overall stability of the cyt c at neutral and slightly alkaline pH.

Original languageEnglish (US)
Pages (from-to)11-20
Number of pages10
JournalBiochimica et Biophysica Acta - Proteins and Proteomics
Issue number1-2
StatePublished - Mar 21 2003


  • Alkaline transition
  • Cytochrome bc
  • Ferricytochrome c
  • Polyglutamate
  • Thermal stability

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biophysics
  • Biochemistry
  • Molecular Biology


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