Home HOME General Physiology and Biophysics 2010 General Physiology and Biophysics Vol.29, No.3, p.255–265, 2010

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Founded: 1982
ISSN  1338-4325 (online)

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General Physiology and Biophysics Vol.29, No.3, p.255–265, 2010

Title: Rate of oxidative modification of cytochrome c by hydrogen peroxide is modulated by Hofmeister anions
Author: Nataša Tomášková, Lenka Varinská, Erik Sedlák

Abstract: Cytochrome c (cyt c) and other heme proteins are oxidatively modified in the presence of hydrogen peroxide in a concentration- and time-dependent manner. Cyt c modification has been monitored by several spectral probes by absorption spectroscopy (at wavelengths 410 nm, 530 nm), and circular dichroism (222, 268, 288 and 417 nm). Kinetics monitored with these spectral probes indicates that the oxidative modification of cyt c: i) proceeds in the order: heme → aromatic amino acids → secondary structure, and ii) the rate of the oxidative modification is proportional to the protein flexibility. The flexibility of cyt c was modulated by anions of Hofmeister series (sulfate, chloride, perchlorate) (Varhač et al. 2009). A minimalist scheme of the interaction of cyt c with hydrogen peroxide can be described by two steps: 1) interaction of hydrogen peroxide with heme iron forming the postulated ferryl intermediate, 2a) oxidation of another molecule of hydrogen peroxide and 2b) parallel oxidation of close amino acid residue(s) and/or heme. The catalase activity of cyt c is independent from the presence of Hofmeister anions, which indicates that both steps (1 and 2a) in the catalase reaction are independent from the flexibility of the heme region of the protein matrix. On the other hand, the flexibility of the polypeptide chain of the protein modulates the rate of parallel oxidative modification of the heme and amino acid residues.

Keywords: Protein flexibility — Protein dynamics — Protein stability — Oxidative damage — Heme proteins
Year: 2010, Volume: 29, Issue: 3 Page From: 255, Page To: 265

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